model.cpp

#include <stdarg.h>
#include <fstream>
#include <regex>
#include <string>
#include <unordered_map>
#include <vector>

#include "model.h"
#include "stable-diffusion.h"
#include "util.h"
#include "vocab.hpp"

#include "ggml/ggml-alloc.h"
#include "ggml/ggml-backend.h"
#include "ggml/ggml.h"

#ifdef SD_USE_METAL
#include "ggml-metal.h"
#endif

#define ST_HEADER_SIZE_LEN 8

uint64_t read_u64(uint8_t* buffer) {
    // little endian
    uint64_t value = 0;
    value |= static_cast<int64_t>(buffer[7]) << 56;
    value |= static_cast<int64_t>(buffer[6]) << 48;
    value |= static_cast<int64_t>(buffer[5]) << 40;
    value |= static_cast<int64_t>(buffer[4]) << 32;
    value |= static_cast<int64_t>(buffer[3]) << 24;
    value |= static_cast<int64_t>(buffer[2]) << 16;
    value |= static_cast<int64_t>(buffer[1]) << 8;
    value |= static_cast<int64_t>(buffer[0]);
    return value;
}

int32_t read_int(uint8_t* buffer) {
    // little endian
    int value = 0;
    value |= buffer[3] << 24;
    value |= buffer[2] << 16;
    value |= buffer[1] << 8;
    value |= buffer[0];
    return value;
}

uint16_t read_short(uint8_t* buffer) {
    // little endian
    uint16_t value = 0;
    value |= buffer[1] << 8;
    value |= buffer[0];
    return value;
}

/*================================================= Preprocess ==================================================*/

std::string self_attn_names[] = {
    "self_attn.q_proj.weight",
    "self_attn.k_proj.weight",
    "self_attn.v_proj.weight",
    "self_attn.q_proj.bias",
    "self_attn.k_proj.bias",
    "self_attn.v_proj.bias",
};

const char* unused_tensors[] = {
    "betas",
    "alphas_cumprod_prev",
    "sqrt_alphas_cumprod",
    "sqrt_one_minus_alphas_cumprod",
    "log_one_minus_alphas_cumprod",
    "sqrt_recip_alphas_cumprod",
    "sqrt_recipm1_alphas_cumprod",
    "posterior_variance",
    "posterior_log_variance_clipped",
    "posterior_mean_coef1",
    "posterior_mean_coef2",
    "cond_stage_model.transformer.text_model.embeddings.position_ids",
    "cond_stage_model.model.logit_scale",
    "cond_stage_model.model.text_projection",
    "conditioner.embedders.0.model.logit_scale",
    "conditioner.embedders.0.model.text_projection",
    "model.diffusion_model.time_embedding.cond_proj.weight",
    "unet.time_embedding.cond_proj.weight",
    "model_ema.decay",
    "model_ema.num_updates",
    "model_ema.diffusion_model",
    "control_model",
    "embedding_manager",
    "denoiser.sigmas",
};

bool is_unused_tensor(std::string name) {
    for (int i = 0; i < sizeof(unused_tensors) / sizeof(const char*); i++) {
        if (starts_with(name, unused_tensors[i])) {
            return true;
        }
    }
    return false;
}

std::unordered_map<std::string, std::string> open_clip_to_hf_clip_model = {
    {"cond_stage_model.model.ln_final.bias", "cond_stage_model.transformer.text_model.final_layer_norm.bias"},
    {"cond_stage_model.model.ln_final.weight", "cond_stage_model.transformer.text_model.final_layer_norm.weight"},
    {"cond_stage_model.model.positional_embedding", "cond_stage_model.transformer.text_model.embeddings.position_embedding.weight"},
    {"cond_stage_model.model.token_embedding.weight", "cond_stage_model.transformer.text_model.embeddings.token_embedding.weight"},

};

std::unordered_map<std::string, std::string> open_clip_to_hk_clip_resblock = {
    {"attn.out_proj.bias", "self_attn.out_proj.bias"},
    {"attn.out_proj.weight", "self_attn.out_proj.weight"},
    {"ln_1.bias", "layer_norm1.bias"},
    {"ln_1.weight", "layer_norm1.weight"},
    {"ln_2.bias", "layer_norm2.bias"},
    {"ln_2.weight", "layer_norm2.weight"},
    {"mlp.c_fc.bias", "mlp.fc1.bias"},
    {"mlp.c_fc.weight", "mlp.fc1.weight"},
    {"mlp.c_proj.bias", "mlp.fc2.bias"},
    {"mlp.c_proj.weight", "mlp.fc2.weight"},
};

std::unordered_map<std::string, std::string> vae_decoder_name_map = {
    {"first_stage_model.decoder.mid.attn_1.to_k.bias", "first_stage_model.decoder.mid.attn_1.k.bias"},
    {"first_stage_model.decoder.mid.attn_1.to_k.weight", "first_stage_model.decoder.mid.attn_1.k.weight"},
    {"first_stage_model.decoder.mid.attn_1.to_out.0.bias", "first_stage_model.decoder.mid.attn_1.proj_out.bias"},
    {"first_stage_model.decoder.mid.attn_1.to_out.0.weight", "first_stage_model.decoder.mid.attn_1.proj_out.weight"},
    {"first_stage_model.decoder.mid.attn_1.to_q.bias", "first_stage_model.decoder.mid.attn_1.q.bias"},
    {"first_stage_model.decoder.mid.attn_1.to_q.weight", "first_stage_model.decoder.mid.attn_1.q.weight"},
    {"first_stage_model.decoder.mid.attn_1.to_v.bias", "first_stage_model.decoder.mid.attn_1.v.bias"},
    {"first_stage_model.decoder.mid.attn_1.to_v.weight", "first_stage_model.decoder.mid.attn_1.v.weight"},
};

std::string convert_open_clip_to_hf_clip(const std::string& name) {
    std::string new_name = name;
    if (starts_with(new_name, "conditioner.embedders.0.")) {
        new_name = "cond_stage_model." + new_name.substr(strlen("conditioner.embedders.0."));
    }
    std::string open_clip_resblock_prefix = "cond_stage_model.model.transformer.resblocks.";
    std::string hf_clip_resblock_prefix   = "cond_stage_model.transformer.text_model.encoder.layers.";

    if (open_clip_to_hf_clip_model.find(new_name) != open_clip_to_hf_clip_model.end()) {
        new_name = open_clip_to_hf_clip_model[new_name];
    }

    if (new_name.find(open_clip_resblock_prefix) == 0) {
        std::string remain = new_name.substr(open_clip_resblock_prefix.length());
        std::string idx    = remain.substr(0, remain.find("."));
        std::string suffix = remain.substr(idx.length() + 1);

        if (suffix == "attn.in_proj_weight" || suffix == "attn.in_proj_bias") {
            new_name = hf_clip_resblock_prefix + idx + "." + suffix;
        } else if (open_clip_to_hk_clip_resblock.find(suffix) != open_clip_to_hk_clip_resblock.end()) {
            std::string new_suffix = open_clip_to_hk_clip_resblock[suffix];
            new_name               = hf_clip_resblock_prefix + idx + "." + new_suffix;
        }
    }

    return new_name;
}

std::string convert_vae_decoder_name(const std::string& name) {
    if (vae_decoder_name_map.find(name) != vae_decoder_name_map.end()) {
        return vae_decoder_name_map[name];
    }
    return name;
}

std::unordered_map<std::string, std::unordered_map<std::string, std::string>> suffix_conversion_underline = {
    {
        "attentions",
        {
            {"to_k", "k"},
            {"to_q", "q"},
            {"to_v", "v"},
            {"to_out_0", "proj_out"},
            {"group_norm", "norm"},
        },
    },
    {
        "resnets",
        {
            {"conv1", "in_layers_2"},
            {"conv2", "out_layers_3"},
            {"norm1", "in_layers_0"},
            {"norm2", "out_layers_0"},
            {"time_emb_proj", "emb_layers_1"},
            {"conv_shortcut", "skip_connection"},
        },
    },
};

std::unordered_map<std::string, std::unordered_map<std::string, std::string>> suffix_conversion_dot = {
    {
        "attentions",
        {
            {"to_k", "k"},
            {"to_q", "q"},
            {"to_v", "v"},
            {"to_out.0", "proj_out"},
            {"group_norm", "norm"},
        },
    },
    {
        "resnets",
        {
            {"conv1", "in_layers.2"},
            {"conv2", "out_layers.3"},
            {"norm1", "in_layers.0"},
            {"norm2", "out_layers.0"},
            {"time_emb_proj", "emb_layers.1"},
            {"conv_shortcut", "skip_connection"},
        },
    },
};

std::string convert_diffusers_name_to_compvis(const std::string& key, char seq) {
    std::vector<std::string> m;

    auto match = [](std::vector<std::string>& match_list, const std::regex& regex, const std::string& key) {
        auto r = std::smatch{};
        if (!std::regex_match(key, r, regex)) {
            return false;
        }

        match_list.clear();
        for (size_t i = 1; i < r.size(); ++i) {
            match_list.push_back(r.str(i));
        }
        return true;
    };

    std::unordered_map<std::string, std::unordered_map<std::string, std::string>> suffix_conversion;
    if (seq == '_') {
        suffix_conversion = suffix_conversion_underline;
    } else {
        suffix_conversion = suffix_conversion_dot;
    }

    auto get_converted_suffix = [&suffix_conversion](const std::string& outer_key, const std::string& inner_key) {
        auto outer_iter = suffix_conversion.find(outer_key);
        if (outer_iter != suffix_conversion.end()) {
            auto inner_iter = outer_iter->second.find(inner_key);
            if (inner_iter != outer_iter->second.end()) {
                return inner_iter->second;
            }
        }
        return inner_key;
    };

    // unet
    if (match(m, std::regex(format("unet%cconv_in(.*)", seq)), key)) {
        return format("model%cdiffusion_model%cinput_blocks%c0%c0", seq, seq, seq, seq) + m[0];
    }

    if (match(m, std::regex(format("unet%cconv%cout(.*)", seq, seq)), key)) {
        return format("model%cdiffusion_model%cout%c2", seq, seq, seq) + m[0];
    }

    if (match(m, std::regex(format("unet%cconv_norm_out(.*)", seq)), key)) {
        return format("model%cdiffusion_model%cout%c0", seq, seq, seq) + m[0];
    }

    if (match(m, std::regex(format("unet%ctime_embedding%clinear_(\\d+)(.*)", seq, seq)), key)) {
        return format("model%cdiffusion_model%ctime_embed%c", seq, seq, seq) + std::to_string(std::stoi(m[0]) * 2 - 2) + m[1];
    }

    if (match(m, std::regex(format("unet%cdown_blocks%c(\\d+)%c(attentions|resnets)%c(\\d+)%c(.+)", seq, seq, seq, seq, seq)), key)) {
        std::string suffix = get_converted_suffix(m[1], m[3]);
        // LOG_DEBUG("%s %s %s %s", m[0].c_str(), m[1].c_str(), m[2].c_str(), m[3].c_str());
        return format("model%cdiffusion_model%cinput_blocks%c", seq, seq, seq) + std::to_string(1 + std::stoi(m[0]) * 3 + std::stoi(m[2])) + seq +
               (m[1] == "attentions" ? "1" : "0") + seq + suffix;
    }

    if (match(m, std::regex(format("unet%cmid_block%c(attentions|resnets)%c(\\d+)%c(.+)", seq, seq, seq, seq)), key)) {
        std::string suffix = get_converted_suffix(m[0], m[2]);
        return format("model%cdiffusion_model%cmiddle_block%c", seq, seq, seq) + (m[0] == "attentions" ? "1" : std::to_string(std::stoi(m[1]) * 2)) +
               seq + suffix;
    }

    if (match(m, std::regex(format("unet%cup_blocks%c(\\d+)%c(attentions|resnets)%c(\\d+)%c(.+)", seq, seq, seq, seq, seq)), key)) {
        std::string suffix = get_converted_suffix(m[1], m[3]);
        return format("model%cdiffusion_model%coutput_blocks%c", seq, seq, seq) + std::to_string(std::stoi(m[0]) * 3 + std::stoi(m[2])) + seq +
               (m[1] == "attentions" ? "1" : "0") + seq + suffix;
    }

    if (match(m, std::regex(format("unet%cdown_blocks%c(\\d+)%cdownsamplers%c0%cconv", seq, seq, seq, seq, seq)), key)) {
        return format("model%cdiffusion_model%cinput_blocks%c", seq, seq, seq) + std::to_string(3 + std::stoi(m[0]) * 3) + seq + "0" + seq + "op";
    }

    if (match(m, std::regex(format("unet%cup_blocks%c(\\d+)%cupsamplers%c0%cconv", seq, seq, seq, seq, seq)), key)) {
        return format("model%cdiffusion_model%coutput_blocks%c", seq, seq, seq) + std::to_string(2 + std::stoi(m[0]) * 3) + seq +
               (std::stoi(m[0]) > 0 ? "2" : "1") + seq + "conv";
    }

    // clip
    if (match(m, std::regex(format("te%ctext_model%cencoder%clayers%c(\\d+)%c(.+)", seq, seq, seq, seq, seq)), key)) {
        return format("cond_stage_model%ctransformer%ctext_model%cencoder%clayers%c", seq, seq, seq, seq, seq) + m[0] + seq + m[1];
    }

    if (match(m, std::regex(format("te%ctext_model(.*)", seq)), key)) {
        return format("cond_stage_model%ctransformer%ctext_model", seq, seq) + m[0];
    }

    // vae
    if (match(m, std::regex(format("vae%c(.*)%cconv_norm_out(.*)", seq, seq)), key)) {
        return format("first_stage_model%c%s%cnorm_out%s", seq, m[0].c_str(), seq, m[1].c_str());
    }

    if (match(m, std::regex(format("vae%c(.*)%cmid_block%c(attentions|resnets)%c(\\d+)%c(.+)", seq, seq, seq, seq, seq)), key)) {
        std::string suffix;
        std::string block_name;
        if (m[1] == "attentions") {
            block_name = "attn";
            suffix     = get_converted_suffix(m[1], m[3]);
        } else {
            block_name = "block";
            suffix     = m[3];
        }
        return format("first_stage_model%c%s%cmid%c%s_%d%c%s",
                      seq, m[0].c_str(), seq, seq, block_name.c_str(), std::stoi(m[2]) + 1, seq, suffix.c_str());
    }

    if (match(m, std::regex(format("vae%c(.*)%cup_blocks%c(\\d+)%cresnets%c(\\d+)%c(.+)", seq, seq, seq, seq, seq, seq)), key)) {
        std::string suffix = m[3];
        if (suffix == "conv_shortcut") {
            suffix = "nin_shortcut";
        }
        return format("first_stage_model%c%s%cup%c%d%cblock%c%s%c%s",
                      seq, m[0].c_str(), seq, seq, 3 - std::stoi(m[1]), seq, seq, m[2].c_str(), seq, suffix.c_str());
    }

    if (match(m, std::regex(format("vae%c(.*)%cdown_blocks%c(\\d+)%cdownsamplers%c0%cconv", seq, seq, seq, seq, seq, seq)), key)) {
        return format("first_stage_model%c%s%cdown%c%d%cdownsample%cconv",
                      seq, m[0].c_str(), seq, seq, std::stoi(m[1]), seq, seq);
    }

    if (match(m, std::regex(format("vae%c(.*)%cdown_blocks%c(\\d+)%cresnets%c(\\d+)%c(.+)", seq, seq, seq, seq, seq, seq)), key)) {
        std::string suffix = m[3];
        if (suffix == "conv_shortcut") {
            suffix = "nin_shortcut";
        }
        return format("first_stage_model%c%s%cdown%c%d%cblock%c%s%c%s",
                      seq, m[0].c_str(), seq, seq, std::stoi(m[1]), seq, seq, m[2].c_str(), seq, suffix.c_str());
    }

    if (match(m, std::regex(format("vae%c(.*)%cup_blocks%c(\\d+)%cupsamplers%c0%cconv", seq, seq, seq, seq, seq, seq)), key)) {
        return format("first_stage_model%c%s%cup%c%d%cupsample%cconv",
                      seq, m[0].c_str(), seq, seq, 3 - std::stoi(m[1]), seq, seq);
    }

    if (match(m, std::regex(format("vae%c(.*)", seq)), key)) {
        return format("first_stage_model%c", seq) + m[0];
    }

    return key;
}

std::string convert_tensor_name(const std::string& name) {
    std::string new_name;
    if (starts_with(name, "cond_stage_model.model") || starts_with(name, "conditioner.embedders.0.model")) {
        new_name = convert_open_clip_to_hf_clip(name);
    } else if (starts_with(name, "first_stage_model.decoder")) {
        new_name = convert_vae_decoder_name(name);
    } else if (starts_with(name, "lora_")) {  // for lora
        size_t pos = name.find('.');
        if (pos != std::string::npos) {
            std::string name_without_network_parts = name.substr(5, pos - 5);
            std::string network_part               = name.substr(pos + 1);
            // LOG_DEBUG("%s %s", name_without_network_parts.c_str(), network_part.c_str());
            std::string new_key = convert_diffusers_name_to_compvis(name_without_network_parts, '_');
            if (new_key.empty()) {
                new_name = name;
            } else {
                new_name = "lora." + new_key + "." + network_part;
            }
        } else {
            new_name = name;
        }
    } else if (starts_with(name, "unet") || starts_with(name, "vae") || starts_with(name, "te")) {  // for diffuser
        size_t pos = name.find_last_of('.');
        if (pos != std::string::npos) {
            std::string name_without_network_parts = name.substr(0, pos);
            std::string network_part               = name.substr(pos + 1);
            // LOG_DEBUG("%s %s", name_without_network_parts.c_str(), network_part.c_str());
            std::string new_key = convert_diffusers_name_to_compvis(name_without_network_parts, '.');
            if (new_key.empty()) {
                new_name = name;
            } else {
                new_name = new_key + "." + network_part;
            }
        } else {
            new_name = name;
        }
    } else {
        new_name = name;
    }
    // if (new_name != name) {
    //     LOG_DEBUG("%s => %s", name.c_str(), new_name.c_str());
    // }
    return new_name;
}

void preprocess_tensor(TensorStorage tensor_storage,
                       std::vector<TensorStorage>& processed_tensor_storages) {
    std::vector<TensorStorage> result;
    std::string new_name = convert_tensor_name(tensor_storage.name);

    // convert unet transformer linear to conv2d 1x1
    if (starts_with(new_name, "model.diffusion_model.") &&
        (ends_with(new_name, "proj_in.weight") || ends_with(new_name, "proj_out.weight"))) {
        tensor_storage.unsqueeze();
    }

    // convert vae attn block linear to conv2d 1x1
    if (starts_with(new_name, "first_stage_model.") && new_name.find("attn_1") != std::string::npos) {
        tensor_storage.unsqueeze();
    }

    tensor_storage.name = new_name;

    if (starts_with(new_name, "cond_stage_model.transformer.text_model.encoder.layers.") &&
        ends_with(new_name, "attn.in_proj_weight")) {
        size_t prefix_size = new_name.find("attn.in_proj_weight");
        std::string prefix = new_name.substr(0, prefix_size);

        std::vector<TensorStorage> chunks = tensor_storage.chunk(3);
        chunks[0].name                    = prefix + "self_attn.q_proj.weight";
        chunks[1].name                    = prefix + "self_attn.k_proj.weight";
        chunks[2].name                    = prefix + "self_attn.v_proj.weight";

        processed_tensor_storages.insert(processed_tensor_storages.end(), chunks.begin(), chunks.end());

    } else if (starts_with(new_name, "cond_stage_model.transformer.text_model.encoder.layers.") &&
               ends_with(new_name, "attn.in_proj_bias")) {
        size_t prefix_size = new_name.find("attn.in_proj_bias");
        std::string prefix = new_name.substr(0, prefix_size);

        std::vector<TensorStorage> chunks = tensor_storage.chunk(3);
        chunks[0].name                    = prefix + "self_attn.q_proj.bias";
        chunks[1].name                    = prefix + "self_attn.k_proj.bias";
        chunks[2].name                    = prefix + "self_attn.v_proj.bias";

        processed_tensor_storages.insert(processed_tensor_storages.end(), chunks.begin(), chunks.end());
    } else {
        processed_tensor_storages.push_back(tensor_storage);
    }
}

float bf16_to_f32(uint16_t bfloat16) {
    uint32_t val_bits = (static_cast<uint32_t>(bfloat16) << 16);
    return *reinterpret_cast<float*>(&val_bits);
}

void bf16_to_f32_vec(uint16_t* src, float* dst, int64_t n) {
    // support inplace op
    for (int64_t i = n - 1; i >= 0; i--) {
        dst[i] = bf16_to_f32(src[i]);
    }
}

void convert_tensor(void* src, ggml_type src_type, void* dst, ggml_type dst_type, int n) {
    if (src_type == dst_type) {
        size_t nbytes = n * ggml_type_size(src_type) / ggml_blck_size(src_type);
        memcpy(((char*)dst), ((char*)src), nbytes);
    } else if (src_type == GGML_TYPE_F32) {
        if (dst_type == GGML_TYPE_F16) {
            ggml_fp32_to_fp16_row((float*)src, (ggml_fp16_t*)dst, n);
        } else {
            int64_t hist[16];
            ggml_quantize_chunk(dst_type, (float*)src, dst, 0, n, hist);
        }
    } else if (dst_type == GGML_TYPE_F32) {
        if (src_type == GGML_TYPE_F16) {
            ggml_fp16_to_fp32_row((ggml_fp16_t*)src, (float*)dst, n);
        } else {
            auto qtype = ggml_internal_get_type_traits(src_type);
            if (qtype.to_float == NULL) {
                throw std::runtime_error(format("type %s unsupported for integer quantization: no dequantization available",
                                                ggml_type_name(src_type)));
            }
            qtype.to_float(src, (float*)dst, n);
        }
    } else {
        // src_type == GGML_TYPE_F16 => dst_type is quantized
        // src_type is quantized => dst_type == GGML_TYPE_F16 or dst_type is quantized
        auto qtype = ggml_internal_get_type_traits(src_type);
        if (qtype.to_float == NULL) {
            throw std::runtime_error(format("type %s unsupported for integer quantization: no dequantization available",
                                            ggml_type_name(src_type)));
        }
        std::vector<char> buf;
        buf.resize(sizeof(float) * n);
        char* src_data_f32 = buf.data();
        qtype.to_float(src, (float*)src_data_f32, n);
        if (dst_type == GGML_TYPE_F16) {
            ggml_fp32_to_fp16_row((float*)src_data_f32, (ggml_fp16_t*)dst, n);
        } else {
            int64_t hist[16];
            ggml_quantize_chunk(dst_type, (float*)src_data_f32, dst, 0, n, hist);
        }
    }
}

/*================================================= ModelLoader ==================================================*/

// ported from https://github.com/openai/CLIP/blob/main/clip/simple_tokenizer.py#L16
std::map<char, int> unicode_to_byte() {
    std::map<int, char> byte_to_unicode;

    // List of utf-8 byte ranges
    for (int b = static_cast<int>('!'); b <= static_cast<int>('~'); ++b) {
        byte_to_unicode[b] = static_cast<char>(b);
    }

    for (int b = 49825; b <= 49836; ++b) {
        byte_to_unicode[b] = static_cast<char>(b);
    }

    for (int b = 49838; b <= 50111; ++b) {
        byte_to_unicode[b] = static_cast<char>(b);
    }
    // printf("%d %d %d %d\n", static_cast<int>('¡'), static_cast<int>('¬'), static_cast<int>('®'), static_cast<int>('ÿ'));
    // exit(1);

    int n = 0;
    for (int b = 0; b < 256; ++b) {
        if (byte_to_unicode.find(b) == byte_to_unicode.end()) {
            byte_to_unicode[b] = static_cast<char>(256 + n);
            n++;
        }
    }

    // byte_encoder = bytes_to_unicode()
    // byte_decoder = {v: k for k, v in byte_encoder.items()}
    std::map<char, int> byte_decoder;

    for (const auto& entry : byte_to_unicode) {
        byte_decoder[entry.second] = entry.first;
    }

    byte_to_unicode.clear();

    return byte_decoder;
}

bool is_zip_file(const std::string& file_path) {
    struct zip_t* zip = zip_open(file_path.c_str(), 0, 'r');
    if (zip == NULL) {
        return false;
    }
    zip_close(zip);
    return true;
}

bool is_gguf_file(const std::string& file_path) {
    std::ifstream file(file_path, std::ios::binary);
    if (!file.is_open()) {
        return false;
    }

    char magic[4];

    file.read(magic, sizeof(magic));
    if (!file) {
        return false;
    }
    for (uint32_t i = 0; i < sizeof(magic); i++) {
        if (magic[i] != GGUF_MAGIC[i]) {
            return false;
        }
    }

    return true;
}

bool is_safetensors_file(const std::string& file_path) {
    std::ifstream file(file_path, std::ios::binary);
    if (!file.is_open()) {
        return false;
    }

    // get file size
    file.seekg(0, file.end);
    size_t file_size_ = file.tellg();
    file.seekg(0, file.beg);

    // read header size
    if (file_size_ <= ST_HEADER_SIZE_LEN) {
        return false;
    }

    uint8_t header_size_buf[ST_HEADER_SIZE_LEN];
    file.read((char*)header_size_buf, ST_HEADER_SIZE_LEN);
    if (!file) {
        return false;
    }

    size_t header_size_ = read_u64(header_size_buf);
    if (header_size_ >= file_size_) {
        return false;
    }

    // read header
    std::vector<char> header_buf;
    header_buf.resize(header_size_ + 1);
    header_buf[header_size_] = '\0';
    file.read(header_buf.data(), header_size_);
    if (!file) {
        return false;
    }
    nlohmann::json header_ = nlohmann::json::parse(header_buf.data());
    if (header_.is_discarded()) {
        return false;
    }
    return true;
}

bool ModelLoader::init_from_file(const std::string& file_path, const std::string& prefix) {
    if (is_directory(file_path)) {
        LOG_INFO("load %s using diffusers format", file_path.c_str());
        return init_from_diffusers_file(file_path, prefix);
    } else if (is_gguf_file(file_path)) {
        LOG_INFO("load %s using gguf format", file_path.c_str());
        return init_from_gguf_file(file_path, prefix);
    } else if (is_safetensors_file(file_path)) {
        LOG_INFO("load %s using safetensors format", file_path.c_str());
        return init_from_safetensors_file(file_path, prefix);
    } else if (is_zip_file(file_path)) {
        LOG_INFO("load %s using checkpoint format", file_path.c_str());
        return init_from_ckpt_file(file_path, prefix);
    } else {
        LOG_WARN("unknown format %s", file_path.c_str());
        return false;
    }
}

/*================================================= GGUFModelLoader ==================================================*/

bool ModelLoader::init_from_gguf_file(const std::string& file_path, const std::string& prefix) {
    LOG_DEBUG("init from '%s'", file_path.c_str());
    file_paths_.push_back(file_path);
    size_t file_index = file_paths_.size() - 1;

    gguf_context* ctx_gguf_ = NULL;
    ggml_context* ctx_meta_ = NULL;
    ctx_gguf_               = gguf_init_from_file(file_path.c_str(), {true, &ctx_meta_});
    if (!ctx_gguf_) {
        LOG_ERROR("failed to open '%s'", file_path.c_str());
        return false;
    }

    int n_tensors = gguf_get_n_tensors(ctx_gguf_);

    size_t total_size  = 0;
    size_t data_offset = gguf_get_data_offset(ctx_gguf_);
    for (int i = 0; i < n_tensors; i++) {
        std::string name          = gguf_get_tensor_name(ctx_gguf_, i);
        struct ggml_tensor* dummy = ggml_get_tensor(ctx_meta_, name.c_str());
        size_t offset             = data_offset + gguf_get_tensor_offset(ctx_gguf_, i);

        // LOG_DEBUG("%s", name.c_str());

        TensorStorage tensor_storage(prefix + name, dummy->type, dummy->ne, dummy->n_dims, file_index, offset);

        GGML_ASSERT(ggml_nbytes(dummy) == tensor_storage.nbytes());

        tensor_storages.push_back(tensor_storage);
    }

    gguf_free(ctx_gguf_);
    ggml_free(ctx_meta_);

    return true;
}

/*================================================= SafeTensorsModelLoader ==================================================*/

ggml_type str_to_ggml_type(const std::string& dtype) {
    ggml_type ttype = GGML_TYPE_COUNT;
    if (dtype == "F16") {
        ttype = GGML_TYPE_F16;
    } else if (dtype == "BF16") {
        ttype = GGML_TYPE_F32;
    } else if (dtype == "F32") {
        ttype = GGML_TYPE_F32;
    }
    return ttype;
}

// https://huggingface.co/docs/safetensors/index
bool ModelLoader::init_from_safetensors_file(const std::string& file_path, const std::string& prefix) {
    LOG_DEBUG("init from '%s'", file_path.c_str());
    file_paths_.push_back(file_path);
    size_t file_index = file_paths_.size() - 1;
    std::ifstream file(file_path, std::ios::binary);
    if (!file.is_open()) {
        LOG_ERROR("failed to open '%s'", file_path.c_str());
        return false;
    }

    // get file size
    file.seekg(0, file.end);
    size_t file_size_ = file.tellg();
    file.seekg(0, file.beg);

    // read header size
    if (file_size_ <= ST_HEADER_SIZE_LEN) {
        LOG_ERROR("invalid safetensor file '%s'", file_path.c_str());
        return false;
    }

    uint8_t header_size_buf[ST_HEADER_SIZE_LEN];
    file.read((char*)header_size_buf, ST_HEADER_SIZE_LEN);
    if (!file) {
        LOG_ERROR("read safetensors header size failed: '%s'", file_path.c_str());
        return false;
    }

    size_t header_size_ = read_u64(header_size_buf);
    if (header_size_ >= file_size_) {
        LOG_ERROR("invalid safetensor file '%s'", file_path.c_str());
        return false;
    }

    // read header
    std::vector<char> header_buf;
    header_buf.resize(header_size_ + 1);
    header_buf[header_size_] = '\0';
    file.read(header_buf.data(), header_size_);
    if (!file) {
        LOG_ERROR("read safetensors header failed: '%s'", file_path.c_str());
        return false;
    }

    nlohmann::json header_ = nlohmann::json::parse(header_buf.data());

    for (auto& item : header_.items()) {
        std::string name           = item.key();
        nlohmann::json tensor_info = item.value();
        // LOG_DEBUG("%s %s\n", name.c_str(), tensor_info.dump().c_str());

        if (name == "__metadata__") {
            continue;
        }

        if (is_unused_tensor(name)) {
            continue;
        }

        std::string dtype    = tensor_info["dtype"];
        nlohmann::json shape = tensor_info["shape"];

        size_t begin = tensor_info["data_offsets"][0].get<size_t>();
        size_t end   = tensor_info["data_offsets"][1].get<size_t>();

        ggml_type type = str_to_ggml_type(dtype);
        if (type == GGML_TYPE_COUNT) {
            LOG_ERROR("unsupported dtype '%s'", dtype.c_str());
            return false;
        }

        if (shape.size() > 4) {
            LOG_ERROR("invalid tensor '%s'", name.c_str());
            return false;
        }

        int n_dims    = (int)shape.size();
        int64_t ne[4] = {1, 1, 1, 1};
        for (int i = 0; i < n_dims; i++) {
            ne[i] = shape[i].get<int64_t>();
        }

        TensorStorage tensor_storage(prefix + name, type, ne, n_dims, file_index, ST_HEADER_SIZE_LEN + header_size_ + begin);

        tensor_storage.reverse_ne();

        size_t tensor_data_size = end - begin;

        if (dtype == "BF16") {
            tensor_storage.is_bf16 = true;
            GGML_ASSERT(tensor_storage.nbytes() == tensor_data_size * 2);
        } else {
            GGML_ASSERT(tensor_storage.nbytes() == tensor_data_size);
        }

        tensor_storages.push_back(tensor_storage);
    }

    return true;
}

/*================================================= DiffusersModelLoader ==================================================*/

bool ModelLoader::init_from_diffusers_file(const std::string& file_path, const std::string& prefix) {
    std::string unet_path = path_join(file_path, "unet/diffusion_pytorch_model.safetensors");
    std::string vae_path  = path_join(file_path, "vae/diffusion_pytorch_model.safetensors");
    std::string clip_path = path_join(file_path, "text_encoder/model.safetensors");

    if (!init_from_safetensors_file(unet_path, "unet.")) {
        return false;
    }
    if (!init_from_safetensors_file(vae_path, "vae.")) {
        return false;
    }
    if (!init_from_safetensors_file(clip_path, "te.")) {
        return false;
    }
    return true;
}

/*================================================= CkptModelLoader ==================================================*/

// $ python -m pickletools sd-v1-4/archive/data.pkl | head -n 100
//     0: \x80 PROTO      2
//     2: }    EMPTY_DICT
//     3: q    BINPUT     0
//     5: (    MARK
//     6: X        BINUNICODE 'epoch'
//    16: q        BINPUT     1
//    18: K        BININT1    6
//    20: X        BINUNICODE 'global_step'
//    36: q        BINPUT     2
//    38: J        BININT     470000
//    43: X        BINUNICODE 'pytorch-lightning_version'
//    73: q        BINPUT     3
//    75: X        BINUNICODE '1.4.2'
//    85: q        BINPUT     4
//    87: X        BINUNICODE 'state_dict'
//   102: q        BINPUT     5
//   104: }        EMPTY_DICT
//   105: q        BINPUT     6
//   107: (        MARK
//   108: X            BINUNICODE 'betas'
//   118: q            BINPUT     7
//   120: c            GLOBAL     'torch._utils _rebuild_tensor_v2'
//   153: q            BINPUT     8
//   155: (            MARK
//   156: (                MARK
//   157: X                    BINUNICODE 'storage'
//   169: q                    BINPUT     9
//   171: c                    GLOBAL     'torch FloatStorage'
//   191: q                    BINPUT     10
//   193: X                    BINUNICODE '0'
//   199: q                    BINPUT     11
//   201: X                    BINUNICODE 'cpu'
//   209: q                    BINPUT     12
//   211: M                    BININT2    1000
//   214: t                    TUPLE      (MARK at 156)
//   215: q                BINPUT     13
//   217: Q                BINPERSID
//   218: K                BININT1    0
//   220: M                BININT2    1000
//  ...............................
//  3201: q            BINPUT     250
//  3203: R            REDUCE
//  3204: q            BINPUT     251
//  3206: X            BINUNICODE 'model.diffusion_model.input_blocks.1.1.proj_in.weight'
//  3264: q            BINPUT     252
//  3266: h            BINGET     8
//  3268: (            MARK
//  3269: (                MARK
//  3270: h                    BINGET     9
//  3272: h                    BINGET     10
//  3274: X                    BINUNICODE '30'
//  3281: q                    BINPUT     253
//  3283: h                    BINGET     12
//  3285: J                    BININT     102400
//  3290: t                    TUPLE      (MARK at 3269)
//  3291: q                BINPUT     254
//  3293: Q                BINPERSID
//  3294: K                BININT1    0
//  3296: (                MARK
//  3297: M                    BININT2    320
//  3300: M                    BININT2    320
//  3303: K                    BININT1    1
//  3305: K                    BININT1    1
//  3307: t                    TUPLE      (MARK at 3296)
//  3308: q                BINPUT     255
//  3310: (                MARK
//  3311: M                    BININT2    320
//  3314: K                    BININT1    1
//  3316: K                    BININT1    1
//  3318: K                    BININT1    1
//  3320: t                    TUPLE      (MARK at 3310)
//  3321: r                LONG_BINPUT 256
//  3326: \x89             NEWFALSE
//  3327: h                BINGET     16
//  3329: )                EMPTY_TUPLE
//  3330: R                REDUCE
//  3331: r                LONG_BINPUT 257
//  3336: t                TUPLE      (MARK at 3268)
//  3337: r            LONG_BINPUT 258
//  3342: R            REDUCE
//  3343: r            LONG_BINPUT 259
//  3348: X            BINUNICODE 'model.diffusion_model.input_blocks.1.1.proj_in.bias'
//  3404: r            LONG_BINPUT 260
//  3409: h            BINGET     8
//  3411: (            MARK
//  3412: (                MARK
//  3413: h                    BINGET     9
//  3415: h                    BINGET     10
//  3417: X                    BINUNICODE '31'

struct PickleTensorReader {
    enum ReadPhase {
        READ_NAME,
        READ_DATA,
        CHECK_SIZE,
        READ_DIMENS
    };
    ReadPhase phase   = READ_NAME;
    size_t entry_size = 0;
    int32_t nelements = 0;

    TensorStorage tensor_storage;

    static ggml_type global_type;  // all pickle_tensors data type
    static bool read_global_type;

    bool read_int_value(uint32_t value) {
        if (phase == CHECK_SIZE) {
            if (entry_size == value * ggml_type_size(tensor_storage.type)) {
                nelements = value;
                phase     = READ_DIMENS;
                return true;
            } else {
                phase = READ_NAME;
            }
        } else if (phase == READ_DIMENS) {
            if (tensor_storage.n_dims + 1 > 4) {  // too many dimens
                phase                 = READ_NAME;
                tensor_storage.n_dims = 0;
            }
            if (nelements % value == 0) {
                tensor_storage.ne[tensor_storage.n_dims] = value;
                tensor_storage.n_dims++;
            }
        }
        return false;
    }

    void read_global(const std::string& str) {
        if (str == "FloatStorage") {
            if (read_global_type) {
                global_type      = GGML_TYPE_F32;
                read_global_type = false;
            }
            tensor_storage.type = GGML_TYPE_F32;
        } else if (str == "HalfStorage") {
            if (read_global_type) {
                global_type      = GGML_TYPE_F16;
                read_global_type = false;
            }
            tensor_storage.type = GGML_TYPE_F16;
        }
    }

    void read_string(const std::string& str, struct zip_t* zip, std::string dir) {
        if (str == "storage") {
            read_global_type = true;
        } else if (str != "state_dict") {
            if (phase == READ_DATA) {
                std::string entry_name = dir + "data/" + std::string(str);

                size_t i, n = zip_entries_total(zip);
                for (i = 0; i < n; ++i) {
                    zip_entry_openbyindex(zip, i);
                    {
                        std::string name = zip_entry_name(zip);
                        if (name == entry_name) {
                            tensor_storage.index_in_zip = (int)i;
                            entry_size                  = zip_entry_size(zip);
                            zip_entry_close(zip);
                            break;
                        }
                    }
                    zip_entry_close(zip);
                }

                phase = entry_size > 0 ? CHECK_SIZE : READ_NAME;
            }
            if (!read_global_type && phase == READ_NAME) {
                tensor_storage.name = str;
                phase               = READ_DATA;
                tensor_storage.type = global_type;
            }
        }
    }
};

ggml_type PickleTensorReader::global_type = GGML_TYPE_F32;  // all pickle_tensors data type
bool PickleTensorReader::read_global_type = false;

int find_char(uint8_t* buffer, int len, char c) {
    for (int pos = 0; pos < len; pos++) {
        if (buffer[pos] == c) {
            return pos;
        }
    }
    return -1;
}

#define MAX_STRING_BUFFER 512

bool ModelLoader::parse_data_pkl(uint8_t* buffer,
                                 size_t buffer_size,
                                 zip_t* zip,
                                 std::string dir,
                                 size_t file_index,
                                 const std::string& prefix) {
    uint8_t* buffer_end = buffer + buffer_size;
    if (buffer[0] == 0x80) {  // proto
        if (buffer[1] != 2) {
            LOG_ERROR("Unsupported protocol\n");
            return false;
        }
        buffer += 2;  // 0x80 and version
        char string_buffer[MAX_STRING_BUFFER];
        bool finish = false;
        PickleTensorReader reader;
        // read pickle binary file
        while (!finish && buffer < buffer_end) {
            uint8_t opcode = *buffer;
            buffer++;
            // https://github.com/python/cpython/blob/3.7/Lib/pickletools.py#L1048
            // https://github.com/python/cpython/blob/main/Lib/pickle.py#L105
            switch (opcode) {
                case '}':  // EMPTY_DICT     = b'}'   # push empty dict
                    break;
                case ']':  // EMPTY_LIST     = b']'   # push empty list
                    break;
                // skip unused sections
                case 'h':  // BINGET         = b'h'   #   "    "    "    "   "   "  ;   "    " 1-byte arg
                case 'q':  // BINPUT         = b'q'   #   "     "    "   "   " ;   "    " 1-byte arg
                case 'Q':  // BINPERSID      = b'Q'   #  "       "         "  ;  "  "   "     "  stack
                    buffer++;
                    break;
                case 'r':  // LONG_BINPUT    = b'r'   #   "     "    "   "   " ;   "    " 4-byte arg
                    buffer += 4;
                    break;
                case 0x95:  // FRAME            = b'\x95'  # indicate the beginning of a new frame
                    buffer += 8;
                    break;
                case 0x94:  // MEMOIZE          = b'\x94'  # store top of the stack in memo
                    break;
                case '(':  // MARK           = b'('   # push special markobject on stack
                    break;
                case 'K':  // BININT1        = b'K'   # push 1-byte unsigned int
                {
                    uint8_t value = *buffer;
                    if (reader.read_int_value(value)) {
                        buffer++;
                    }
                    buffer++;
                } break;
                case 'M':  // BININT2        = b'M'   # push 2-byte unsigned int
                {
                    uint16_t value = read_short(buffer);
                    if (reader.read_int_value(value)) {
                        buffer++;
                    }
                    buffer += 2;
                } break;
                case 'J':  // BININT         = b'J'   # push four-byte signed int
                {
                    const int32_t value = read_int(buffer);
                    if (reader.read_int_value(value)) {
                        buffer++;  // skip tuple after read num_elements
                    }
                    buffer += 4;
                } break;
                case 'X':  // BINUNICODE     = b'X'   #   "     "       "  ; counted UTF-8 string argument
                {
                    const int32_t len = read_int(buffer);
                    buffer += 4;
                    memset(string_buffer, 0, MAX_STRING_BUFFER);
                    if (len > MAX_STRING_BUFFER) {
                        LOG_WARN("tensor name very large");
                    }
                    memcpy(string_buffer, buffer, len < MAX_STRING_BUFFER ? len : (MAX_STRING_BUFFER - 1));
                    buffer += len;
                    reader.read_string(string_buffer, zip, dir);
                } break;
                case 0x8C:  // SHORT_BINUNICODE = b'\x8c'  # push short string; UTF-8 length < 256 bytes
                {
                    const int8_t len = *buffer;
                    buffer++;
                    memset(string_buffer, 0, MAX_STRING_BUFFER);
                    memcpy(string_buffer, buffer, len);
                    buffer += len;
                    // printf("String: '%s'\n", string_buffer);
                } break;
                case 'c':  // GLOBAL         = b'c'   # push self.find_class(modname, name); 2 string args
                {
                    int len = find_char(buffer, MAX_STRING_BUFFER, '\n');

                    buffer += len + 1;
                    len = find_char(buffer, MAX_STRING_BUFFER, '\n');

                    memset(string_buffer, 0, MAX_STRING_BUFFER);
                    memcpy(string_buffer, buffer, len);
                    buffer += len + 1;
                    reader.read_global(string_buffer);
                } break;
                case 0x86:  // TUPLE2         = b'\x86'  # build 2-tuple from two topmost stack items
                case 0x85:  // TUPLE1         = b'\x85'  # build 1-tuple from stack top
                case 't':   // TUPLE          = b't'   # build tuple from topmost stack items
                    if (reader.phase == PickleTensorReader::READ_DIMENS) {
                        reader.tensor_storage.reverse_ne();
                        reader.tensor_storage.file_index = file_index;
                        reader.tensor_storage.name       = prefix + reader.tensor_storage.name;
                        tensor_storages.push_back(reader.tensor_storage);
                        // LOG_DEBUG("%s", reader.tensor_storage.name.c_str());
                        // reset
                        reader = PickleTensorReader();
                    }
                    break;
                case '.':  // STOP           = b'.'   # every pickle ends with STOP
                    finish = true;
                    break;
                default:
                    break;
            }
        }
    }
    return true;
}

bool ModelLoader::init_from_ckpt_file(const std::string& file_path, const std::string& prefix) {
    LOG_DEBUG("init from '%s'", file_path.c_str());
    file_paths_.push_back(file_path);
    size_t file_index = file_paths_.size() - 1;

    struct zip_t* zip = zip_open(file_path.c_str(), 0, 'r');
    if (zip == NULL) {
        LOG_ERROR("failed to open '%s'", file_path.c_str());
        return false;
    }
    int n = (int)zip_entries_total(zip);
    for (int i = 0; i < n; ++i) {
        zip_entry_openbyindex(zip, i);
        {
            std::string name = zip_entry_name(zip);
            size_t pos       = name.find("data.pkl");
            if (pos != std::string::npos) {
                std::string dir = name.substr(0, pos);
                void* pkl_data  = NULL;
                size_t pkl_size;
                zip_entry_read(zip, &pkl_data, &pkl_size);

                // LOG_DEBUG("%lld", pkl_size);

                parse_data_pkl((uint8_t*)pkl_data, pkl_size, zip, dir, file_index, prefix);

                free(pkl_data);
            }
        }
        zip_entry_close(zip);
    }
    zip_close(zip);
    return true;
}

SDVersion ModelLoader::get_sd_version() {
    TensorStorage token_embedding_weight;
    for (auto& tensor_storage : tensor_storages) {
        if (tensor_storage.name == "cond_stage_model.transformer.text_model.embeddings.token_embedding.weight" ||
            tensor_storage.name == "cond_stage_model.model.token_embedding.weight" ||
            tensor_storage.name == "text_model.embeddings.token_embedding.weight" ||
            tensor_storage.name == "te.text_model.embeddings.token_embedding.weight" ||
            tensor_storage.name == "conditioner.embedders.0.model.token_embedding.weight") {
            token_embedding_weight = tensor_storage;
            break;
        }
    }
    if (token_embedding_weight.ne[0] == 768) {
        return VERSION_1_x;
    } else if (token_embedding_weight.ne[0] == 1024) {
        return VERSION_2_x;
    }
    return VERSION_COUNT;
}

ggml_type ModelLoader::get_sd_wtype() {
    for (auto& tensor_storage : tensor_storages) {
        if (is_unused_tensor(tensor_storage.name)) {
            continue;
        }

        if (tensor_storage.name.find(".weight") != std::string::npos &&
            tensor_storage.name.find("time_embed") != std::string::npos) {
            return tensor_storage.type;
        }
    }
    return GGML_TYPE_COUNT;
}

std::string ModelLoader::load_merges() {
    std::string merges_utf8_str(reinterpret_cast<const char*>(merges_utf8_c_str), sizeof(merges_utf8_c_str));
    return merges_utf8_str;
}

bool ModelLoader::load_tensors(on_new_tensor_cb_t on_new_tensor_cb, ggml_backend_t backend) {
    bool success = true;
    for (size_t file_index = 0; file_index < file_paths_.size(); file_index++) {
        std::string file_path = file_paths_[file_index];
        LOG_DEBUG("loading tensors from %s", file_path.c_str());

        std::ifstream file(file_path, std::ios::binary);
        if (!file.is_open()) {
            LOG_ERROR("failed to open '%s'", file_path.c_str());
            return false;
        }

        bool is_zip = false;
        for (auto& tensor_storage : tensor_storages) {
            if (tensor_storage.file_index != file_index) {
                continue;
            }
            if (tensor_storage.index_in_zip >= 0) {
                is_zip = true;
                break;
            }
        }

        struct zip_t* zip = NULL;
        if (is_zip) {
            zip = zip_open(file_path.c_str(), 0, 'r');
            if (zip == NULL) {
                LOG_ERROR("failed to open zip '%s'", file_path.c_str());
                return false;
            }
        }

        std::vector<uint8_t> read_buffer;
        std::vector<uint8_t> convert_buffer;

        auto read_data = [&](const TensorStorage& tensor_storage, char* buf, size_t n) {
            if (zip != NULL) {
                zip_entry_openbyindex(zip, tensor_storage.index_in_zip);
                size_t entry_size = zip_entry_size(zip);
                if (entry_size != n) {
                    read_buffer.resize(entry_size);
                    zip_entry_noallocread(zip, (void*)read_buffer.data(), entry_size);
                    memcpy((void*)buf, (void*)(read_buffer.data() + tensor_storage.offset), n);
                } else {
                    zip_entry_noallocread(zip, (void*)buf, n);
                }
                zip_entry_close(zip);
            } else {
                file.seekg(tensor_storage.offset);
                file.read(buf, n);
                if (!file) {
                    LOG_ERROR("read tensor data failed: '%s'", file_path.c_str());
                    return false;
                }
            }
            return true;
        };

        std::vector<TensorStorage> processed_tensor_storages;
        for (auto& tensor_storage : tensor_storages) {
            if (tensor_storage.file_index != file_index) {
                continue;
            }

            // LOG_DEBUG("%s", name.c_str());

            if (is_unused_tensor(tensor_storage.name)) {
                continue;
            }

            preprocess_tensor(tensor_storage, processed_tensor_storages);
        }

        for (auto& tensor_storage : processed_tensor_storages) {
            // LOG_DEBUG("%s", name.c_str());

            ggml_tensor* dst_tensor = NULL;

            success = on_new_tensor_cb(tensor_storage, &dst_tensor);
            if (!success) {
                LOG_WARN("process tensor failed: '%s'", tensor_storage.name.c_str());
                break;
            }

            if (dst_tensor == NULL) {
                continue;
            }

            size_t nbytes_to_read = tensor_storage.nbytes_to_read();

            if (dst_tensor->buffer == NULL || ggml_backend_is_cpu(backend)
#ifdef SD_USE_METAL
                || ggml_backend_is_metal(backend)
#endif
            ) {
                // for the CPU and Metal backend, we can copy directly into the tensor
                if (tensor_storage.type == dst_tensor->type) {
                    GGML_ASSERT(ggml_nbytes(dst_tensor) == tensor_storage.nbytes());
                    read_data(tensor_storage, (char*)dst_tensor->data, nbytes_to_read);

                    if (tensor_storage.is_bf16) {
                        // inplace op
                        bf16_to_f32_vec((uint16_t*)dst_tensor->data, (float*)dst_tensor->data, tensor_storage.nelements());
                    }
                } else {
                    read_buffer.resize(tensor_storage.nbytes());
                    read_data(tensor_storage, (char*)read_buffer.data(), nbytes_to_read);

                    if (tensor_storage.is_bf16) {
                        // inplace op
                        bf16_to_f32_vec((uint16_t*)read_buffer.data(), (float*)read_buffer.data(), tensor_storage.nelements());
                    }

                    convert_tensor((void*)read_buffer.data(), tensor_storage.type, dst_tensor->data,
                                   dst_tensor->type, (int)tensor_storage.nelements());
                }
            } else {
                read_buffer.resize(tensor_storage.nbytes());
                read_data(tensor_storage, (char*)read_buffer.data(), nbytes_to_read);

                if (tensor_storage.is_bf16) {
                    // inplace op
                    bf16_to_f32_vec((uint16_t*)read_buffer.data(), (float*)read_buffer.data(), tensor_storage.nelements());
                }

                if (tensor_storage.type == dst_tensor->type) {
                    // copy to device memory
                    ggml_backend_tensor_set(dst_tensor, read_buffer.data(), 0, ggml_nbytes(dst_tensor));
                } else {
                    // convert first, then copy to device memory
                    convert_buffer.resize(ggml_nbytes(dst_tensor));
                    convert_tensor((void*)read_buffer.data(), tensor_storage.type,
                                   (void*)convert_buffer.data(), dst_tensor->type,
                                   (int)tensor_storage.nelements());
                    ggml_backend_tensor_set(dst_tensor, convert_buffer.data(), 0, ggml_nbytes(dst_tensor));
                }
            }
        }

        if (zip != NULL) {
            zip_close(zip);
        }

        if (!success) {
            break;
        }
    }
    return success;
}

int64_t ModelLoader::cal_mem_size(ggml_backend_t backend) {
    size_t alignment = 128;
    if (backend != NULL) {
        alignment = ggml_backend_get_alignment(backend);
    }
    int64_t mem_size = 0;
    std::vector<TensorStorage> processed_tensor_storages;
    for (auto& tensor_storage : tensor_storages) {
        if (is_unused_tensor(tensor_storage.name)) {
            continue;
        }
        preprocess_tensor(tensor_storage, processed_tensor_storages);
    }

    for (auto& tensor_storage : processed_tensor_storages) {
        mem_size += tensor_storage.nbytes() + alignment;
    }

    return mem_size;
}