Merge pull request #646 from armijnhemel/pif

add Portable Image Format (pif)

image/pif.ksy

@@ -0,0 +1,173 @@
+meta:
+  id: pif
+  title: Portable Image Format
+  file-extension: pif
+  xref:
+    justsolve: PIF_(Portable_Image_Format)
+  license: LGPL-2.1
+  ks-version: 0.9
+  endian: le
+  bit-endian: le
+doc: |
+  The Portable Image Format (PIF) is a basic, bitmap-like image format with the
+  focus on ease of use (implementation) and small size for embedded
+  applications.
+
+  See <https://github.com/gfcwfzkm/PIF-Image-Format> for more info.
+doc-ref:
+  - https://github.com/gfcwfzkm/PIF-Image-Format/blob/cc256d5/Specification/PIF%20Format%20Specification.pdf
+  - https://github.com/gfcwfzkm/PIF-Image-Format/blob/cc256d5/C%20Library/pifdec.c#L300
+seq:
+  - id: file_header
+    type: pif_header
+  - id: info_header
+    type: information_header
+  - id: color_table
+    size: info_header.len_color_table
+    type: color_table_data
+    if: info_header.uses_indexed_mode
+instances:
+  image_data:
+    pos: file_header.ofs_image_data
+    size: info_header.len_image_data
+types:
+  pif_header:
+    seq:
+      - id: magic
+        contents: ["PIF", 0x00]
+      - id: len_file
+        type: u4
+        valid:
+          min: ofs_image_data_min
+      - id: ofs_image_data
+        type: u4
+        valid:
+          min: ofs_image_data_min
+          max: len_file
+    instances:
+      ofs_image_data_min:
+        value: _root.file_header._sizeof + _root.info_header._sizeof
+  information_header:
+    seq:
+      - id: image_type
+        type: u2
+        enum: image_type
+        valid:
+          any-of:
+            - image_type::rgb888
+            - image_type::rgb565
+            - image_type::rgb332
+            - image_type::rgb16c
+            - image_type::black_white
+            - image_type::indexed_rgb888
+            - image_type::indexed_rgb565
+            - image_type::indexed_rgb332
+      - id: bits_per_pixel
+        type: u2
+        valid:
+          expr: |
+            image_type == image_type::rgb888 ? _ == 24 :
+            image_type == image_type::rgb565 ? _ == 16 :
+            image_type == image_type::rgb332 ? _ == 8 :
+            image_type == image_type::rgb16c ? _ == 4 :
+            image_type == image_type::black_white ? _ == 1 :
+            uses_indexed_mode ? _ <= 8 :
+            true
+          # ^ shouldn't get there (all cases have been covered before)
+        doc: |
+          See <https://github.com/gfcwfzkm/PIF-Image-Format/blob/cc256d5/Specification/PIF%20Format%20Specification.pdf>:
+
+          > Bits per Pixel: Bit size that each Pixel occupies. Bit size for an
+          > Indexed Image cannot go beyond 8 bits.
+      - id: width
+        type: u2
+      - id: height
+        type: u2
+      - id: len_image_data
+        type: u4
+        valid:
+          max: _root.file_header.len_file - _root.file_header.ofs_image_data
+      - id: len_color_table
+        type: u2
+        valid:
+          min: 'uses_indexed_mode ? len_color_table_entry * 1 : 0'
+          max: |
+            uses_indexed_mode ? (
+              len_color_table_max < len_color_table_full
+                ? len_color_table_max
+                : len_color_table_full
+            ) : 0
+        doc: |
+          See <https://github.com/gfcwfzkm/PIF-Image-Format/blob/cc256d5/Specification/PIF%20Format%20Specification.pdf>:
+
+          > Color Table Size: (...), only used in Indexed mode, otherwise zero.
+          ---
+          > **Note**: The presence of the Color Table is mandatory when Bits per
+          > Pixel <= 8, unless Image Type states RGB332, RGB16C or B/W
+          ---
+          > **Color Table** (semi-optional)
+          >
+          > (...) The amount of Colors has to be same or less than [Bits per
+          > Pixel] allow, otherwise the image is invalid.
+      - id: compression
+        type: u2
+        enum: compression_type
+        valid:
+          any-of:
+            - compression_type::none
+            - compression_type::rle
+    instances:
+      len_color_table_entry:
+        value: |
+          image_type == image_type::indexed_rgb888 ? 3 :
+          image_type == image_type::indexed_rgb565 ? 2 :
+          image_type == image_type::indexed_rgb332 ? 1 :
+          0
+      len_color_table_full:
+        value: len_color_table_entry * (1 << bits_per_pixel)
+      len_color_table_max:
+        value: _root.file_header.ofs_image_data - _root.file_header.ofs_image_data_min
+      uses_indexed_mode:
+        value: len_color_table_entry != 0
+      num_color_table_entries:
+        value: len_color_table / len_color_table_entry
+        if: uses_indexed_mode
+  color_table_data:
+    seq:
+      - id: entries
+        type:
+          switch-on: _root.info_header.image_type
+          cases:
+            image_type::indexed_rgb888: b24
+            image_type::indexed_rgb565: b16
+            image_type::indexed_rgb332: b8
+        repeat: expr
+        repeat-expr: _root.info_header.num_color_table_entries
+enums:
+  image_type:
+    0x433c: rgb888
+    0xe5c5: rgb565
+    0x1e53: rgb332
+    0xb895:
+      id: rgb16c
+      doc: |
+        Formula to convert the 4-bit color value in RGB16C mode to RGB values
+        (each in the range from 0 to 255):
+
+        ```
+        red   = 170 * ((color_value & 0b0100) >> 2) + 85 * ((color_value & 0b1000) >> 3)
+        green = 170 * ((color_value & 0b0010) >> 1) + 85 * ((color_value & 0b1000) >> 3)
+        blue  = 170 * ((color_value & 0b0001) >> 0) + 85 * ((color_value & 0b1000) >> 3)
+        ```
+
+        See also <https://en.wikipedia.org/wiki/Color_Graphics_Adapter#Color_palette>
+    0x7daa:
+      id: black_white
+      doc: '0: black, 1: white'
+      doc-ref: https://github.com/gfcwfzkm/PIF-Image-Format/blob/cc256d5/C%20Library/pifdec.c#L233
+    0x4952: indexed_rgb888
+    0x4947: indexed_rgb565
+    0x4942: indexed_rgb332
+  compression_type:
+    0x0000: none
+    0x7dde: rle