nes cartridge: support loading binary buffer without header

retroenv · Nov 5, 2024 · 931e147 · 931e147
1 parent cddedcd
commit 931e147
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Showing 2 changed files with 47 additions and 0 deletions.
diff --git a/arch/nes/cartridge/ines.go b/arch/nes/cartridge/ines.go
@@ -75,3 +75,31 @@ func LoadFile(reader io.Reader) (*Cartridge, error) {
 		VideoFormat: header.VideoFormat,
 	}, nil
 }
+
+// LoadBuffer loads an raw binary buffer.
+func LoadBuffer(reader io.Reader) (*Cartridge, error) {
+	b, err := io.ReadAll(reader)
+	if err != nil {
+		return nil, fmt.Errorf("reading PRG: %w", err)
+	}
+
+	size := len(b) / 16384
+	if len(b)%16384 != 0 {
+		size++
+	}
+	size *= 16384
+
+	prg := make([]byte, size)
+	copy(prg, b)
+
+	return &Cartridge{
+		PRG:         prg,
+		CHR:         make([]byte, 8192),
+		RAM:         0,
+		Trainer:     nil,
+		Mapper:      0,
+		Mirror:      MirrorVertical,
+		Battery:     0,
+		VideoFormat: 0,
+	}, nil
+}
diff --git a/arch/nes/cartridge/ines_test.go b/arch/nes/cartridge/ines_test.go
@@ -49,3 +49,22 @@ func TestCartridgeSave(t *testing.T) {
 	b := buf.Bytes()
 	assert.Equal(t, rom, b)
 }
+
+func TestLoadBuffer(t *testing.T) {
+	// test a small buffer
+	buf := []byte{0x60}
+	reader := bytes.NewReader(buf)
+
+	cart, err := LoadBuffer(reader)
+	assert.NoError(t, err)
+	assert.Equal(t, 0x60, cart.PRG[0])
+
+	// test a large buffer
+	buf = make([]byte, 16384+1000)
+	buf[0] = 0x60
+	reader = bytes.NewReader(buf)
+
+	cart, err = LoadBuffer(reader)
+	assert.NoError(t, err)
+	assert.Equal(t, 0x60, cart.PRG[0])
+}