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Rewrite fmp_chunk.go to use switch, add delayed

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This commit is contained in:
Romein van Buren
2025-06-13 14:44:32 +02:00
parent 41041e124c
commit 88ea33c76e
3 changed files with 187 additions and 212 deletions
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379
fmp/fmp_chunk.go
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@ -2,229 +2,194 @@ package fmp
func (ctx *FmpFile) readChunk(payload []byte) (*FmpChunk, error) {
// Simple data
// https://github.com/evanmiller/fmptools/blob/02eb770e59e0866dab213d80e5f7d88e17648031/HACKING
// https://github.com/Rasmus20B/fmplib/blob/66245e5269275724bacfe1437fb1f73bc587a2f3/src/fmp_format/chunk.rs#L57-L60
if payload[0] == 0x00 || payload[0] == 0x19 || payload[0] == 0x23 {
return &FmpChunk{
Type: FMP_CHUNK_SIMPLE_DATA,
Value: payload[1 : 1+1],
Length: 2,
}, nil
}
if payload[0] == 0x08 {
return &FmpChunk{
Type: FMP_CHUNK_SIMPLE_DATA,
Value: payload[1 : 1+2],
Length: 3,
}, nil
}
if payload[0] == 0x0E && payload[1] == 0xFF {
return &FmpChunk{
Type: FMP_CHUNK_SIMPLE_DATA,
Value: payload[2 : 2+5],
Length: 7,
}, nil
}
if 0x10 <= payload[0] && payload[0] <= 0x11 {
valueLength := 3 + (payload[0] - 0x10)
return &FmpChunk{
Type: FMP_CHUNK_SIMPLE_DATA,
Value: payload[1 : 1+valueLength],
Length: 1 + uint64(valueLength),
}, nil
}
if 0x12 <= payload[0] && payload[0] <= 0x15 {
valueLength := 1 + 2*(payload[0]-0x10)
return &FmpChunk{
Type: FMP_CHUNK_SIMPLE_DATA,
Value: payload[1 : 1+valueLength],
Length: 1 + uint64(valueLength),
}, nil
}
if 0x1A <= payload[0] && payload[0] <= 0x1D {
valueLength := 2 * (payload[0] - 0x19)
return &FmpChunk{
Type: FMP_CHUNK_SIMPLE_DATA,
Value: payload[1 : 1+valueLength],
Length: 1 + uint64(valueLength),
}, nil
chunk := &FmpChunk{}
if (payload[0] & 0xC0) == 0xC0 {
payload[0] &= 0x3F
chunk.Delayed = true
}
// Simple key-value
switch payload[0] {
case 0x00:
chunk.Type = FMP_CHUNK_SIMPLE_DATA
chunk.Value = payload[1 : 1+1]
chunk.Length = 2
if payload[0] == 0x01 {
return &FmpChunk{
Type: FMP_CHUNK_SIMPLE_KEY_VALUE,
Key: uint64(payload[1]),
Value: payload[2 : 2+1],
Length: 3,
}, nil
}
if 0x02 <= payload[0] && payload[0] <= 0x05 {
case 0x01:
chunk.Type = FMP_CHUNK_SIMPLE_KEY_VALUE
chunk.Key = uint64(payload[1])
chunk.Value = payload[2 : 2+1]
chunk.Length = 3
case 0x02, 0x03, 0x04, 0x05:
valueLength := 2 * (payload[0] - 1)
return &FmpChunk{
Type: FMP_CHUNK_SIMPLE_KEY_VALUE,
Key: uint64(payload[1]),
Value: payload[2 : 2+valueLength],
Length: 2 + uint64(valueLength),
}, nil
}
if payload[0] == 0x06 {
chunk.Type = FMP_CHUNK_SIMPLE_KEY_VALUE
chunk.Key = uint64(payload[1])
chunk.Value = payload[2 : 2+valueLength]
chunk.Length = 2 + uint64(valueLength)
case 0x06:
valueLength := payload[2]
return &FmpChunk{
Type: FMP_CHUNK_SIMPLE_KEY_VALUE,
Key: uint64(payload[1]),
Value: payload[2 : 2+valueLength], // docs say offset 2?
Length: 3 + uint64(valueLength),
}, nil
}
if payload[0] == 0x09 {
return &FmpChunk{
Type: FMP_CHUNK_SIMPLE_KEY_VALUE,
Key: parseVarUint64(payload[1 : 1+2]),
Value: payload[3 : 3+1],
Length: 4,
}, nil
}
if 0x0A <= payload[0] && payload[0] <= 0x0D {
valueLength := 2 * (payload[0] - 0x09)
return &FmpChunk{
Type: FMP_CHUNK_SIMPLE_KEY_VALUE,
Key: parseVarUint64(payload[1 : 1+2]),
Value: payload[3 : 3+valueLength],
Length: 2 + uint64(valueLength),
}, nil
}
if payload[0] == 0x0E {
valueLength := payload[2]
return &FmpChunk{
Type: FMP_CHUNK_SIMPLE_KEY_VALUE,
Key: parseVarUint64(payload[1 : 1+2]),
Value: payload[4 : 4+valueLength],
Length: 4 + uint64(valueLength),
}, nil
}
chunk.Type = FMP_CHUNK_SIMPLE_KEY_VALUE
chunk.Key = uint64(payload[1])
chunk.Value = payload[3 : 3+valueLength]
chunk.Length = 3 + uint64(valueLength)
// Long key-value
if payload[0] == 0x16 {
valueLength := payload[4]
return &FmpChunk{
Type: FMP_CHUNK_LONG_KEY_VALUE,
Key: parseVarUint64(payload[1 : 1+3]),
Value: payload[5 : 5+valueLength],
Length: 5 + uint64(valueLength),
}, nil
}
if payload[0] == 0x17 {
valueLength := parseVarUint64(payload[4 : 4+2])
return &FmpChunk{
Type: FMP_CHUNK_LONG_KEY_VALUE,
Key: parseVarUint64(payload[1 : 1+3]),
Value: payload[6 : 6+valueLength],
Length: 6 + uint64(valueLength),
}, nil
}
if payload[0] == 0x1E {
keyLength := payload[1]
valueLength := payload[2+keyLength]
return &FmpChunk{
Type: FMP_CHUNK_LONG_KEY_VALUE,
Key: parseVarUint64(payload[2 : 2+keyLength]),
Value: payload[2+keyLength+1 : 2+keyLength+1+valueLength],
Length: 2 + uint64(keyLength) + 1 + uint64(valueLength),
}, nil
}
if payload[0] == 0x1F {
keyLength := uint64(payload[1])
valueLength := parseVarUint64(payload[2+keyLength : 2+keyLength+2+1])
return &FmpChunk{
Type: FMP_CHUNK_LONG_KEY_VALUE,
Key: parseVarUint64(payload[2 : 2+keyLength]),
Value: payload[2+keyLength+2 : 2+keyLength+2+valueLength],
Length: 4 + uint64(keyLength) + uint64(valueLength),
}, nil
}
// Segmented data
if payload[0] == 0x07 {
case 0x07:
valueLength := parseVarUint64(payload[2 : 2+2])
payloadLimit := min(4+valueLength, uint64(len(payload)))
return &FmpChunk{
Type: FMP_CHUNK_SEGMENTED_DATA,
Index: uint64(payload[1]),
Value: payload[4:payloadLimit],
Length: 4 + uint64(valueLength),
}, nil
}
if payload[0] == 0x0F {
chunk.Type = FMP_CHUNK_SEGMENTED_DATA
chunk.Index = uint64(payload[1])
chunk.Value = payload[4:payloadLimit]
chunk.Length = 4 + uint64(valueLength)
case 0x08:
chunk.Type = FMP_CHUNK_SIMPLE_DATA
chunk.Value = payload[1 : 1+2]
chunk.Length = 3
case 0x09:
chunk.Type = FMP_CHUNK_SIMPLE_KEY_VALUE
chunk.Key = parseVarUint64(payload[1 : 1+2])
chunk.Value = payload[3 : 3+1]
chunk.Length = 4
case 0x0A, 0x0B, 0x0C, 0x0D:
valueLength := 2 * (payload[0] - 0x09)
chunk.Type = FMP_CHUNK_SIMPLE_KEY_VALUE
chunk.Key = parseVarUint64(payload[1 : 1+2])
chunk.Value = payload[3 : 3+valueLength]
chunk.Length = 2 + uint64(valueLength)
case 0x0E:
if payload[1] == 0xFE {
chunk.Type = FMP_CHUNK_PATH_PUSH
chunk.Value = payload[1 : 1+8]
chunk.Length = 10
break
}
if payload[1] == 0xFF {
chunk.Type = FMP_CHUNK_SIMPLE_DATA
chunk.Value = payload[2 : 2+5]
chunk.Length = 7
break
}
valueLength := payload[2]
chunk.Type = FMP_CHUNK_SIMPLE_KEY_VALUE
chunk.Key = parseVarUint64(payload[1 : 1+2])
chunk.Value = payload[4 : 4+valueLength]
chunk.Length = 4 + uint64(valueLength)
case 0x0F:
valueLength := parseVarUint64(payload[3 : 3+2])
payloadLimit := min(5+valueLength, uint64(len(payload)))
return &FmpChunk{
Type: FMP_CHUNK_SEGMENTED_DATA,
Index: parseVarUint64(payload[1 : 1+2]),
Value: payload[5:payloadLimit],
Length: 5 + valueLength,
}, nil
}
chunk.Type = FMP_CHUNK_SEGMENTED_DATA
chunk.Index = parseVarUint64(payload[1 : 1+2])
chunk.Value = payload[5:payloadLimit]
chunk.Length = 5 + valueLength
// Path push
case 0x10, 0x11:
valueLength := 3 + (payload[0] - 0x10)
chunk.Type = FMP_CHUNK_SIMPLE_DATA
chunk.Value = payload[1 : 1+valueLength]
chunk.Length = 1 + uint64(valueLength)
if payload[0] == 0x20 || payload[0] == 0x0E {
case 0x12, 0x13, 0x14, 0x15:
valueLength := 1 + 2*(payload[0]-0x10)
chunk.Type = FMP_CHUNK_SIMPLE_DATA
chunk.Value = payload[1 : 1+valueLength]
chunk.Length = 1 + uint64(valueLength)
case 0x16:
valueLength := payload[4]
chunk.Type = FMP_CHUNK_LONG_KEY_VALUE
chunk.Key = parseVarUint64(payload[1 : 1+3])
chunk.Value = payload[5 : 5+valueLength]
chunk.Length = 5 + uint64(valueLength)
case 0x17:
valueLength := parseVarUint64(payload[4 : 4+2])
chunk.Type = FMP_CHUNK_LONG_KEY_VALUE
chunk.Key = parseVarUint64(payload[1 : 1+3])
chunk.Value = payload[6 : 6+valueLength]
chunk.Length = 6 + uint64(valueLength)
case 0x19:
chunk.Type = FMP_CHUNK_SIMPLE_DATA
chunk.Value = payload[1 : 1+1]
chunk.Length = 2
case 0x1A, 0x1B, 0x1C, 0x1D:
valueLength := 2 * (payload[0] - 0x19)
chunk.Type = FMP_CHUNK_SIMPLE_DATA
chunk.Value = payload[1 : 1+valueLength]
chunk.Length = 1 + uint64(valueLength)
case 0x1E:
keyLength := payload[1]
valueLength := payload[2+keyLength]
chunk.Type = FMP_CHUNK_LONG_KEY_VALUE
chunk.Key = parseVarUint64(payload[2 : 2+keyLength])
chunk.Value = payload[2+keyLength+1 : 2+keyLength+1+valueLength]
chunk.Length = 2 + uint64(keyLength) + 1 + uint64(valueLength)
case 0x1F:
keyLength := uint64(payload[1])
valueLength := parseVarUint64(payload[2+keyLength : 2+keyLength+2+1])
chunk.Type = FMP_CHUNK_LONG_KEY_VALUE
chunk.Key = parseVarUint64(payload[2 : 2+keyLength])
chunk.Value = payload[2+keyLength+2 : 2+keyLength+2+valueLength]
chunk.Length = 4 + uint64(keyLength) + uint64(valueLength)
case 0x20:
if payload[1] == 0xFE {
return &FmpChunk{
Type: FMP_CHUNK_PATH_PUSH,
Value: payload[1 : 1+8],
Length: 10,
}, nil
chunk.Type = FMP_CHUNK_PATH_PUSH
chunk.Value = payload[1 : 1+8]
chunk.Length = 10
break
}
return &FmpChunk{
Type: FMP_CHUNK_PATH_PUSH,
Value: payload[1 : 1+1],
Length: 2,
}, nil
}
if payload[0] == 0x28 {
return &FmpChunk{
Type: FMP_CHUNK_PATH_PUSH,
Value: payload[1 : 1+2],
Length: 3,
}, nil
}
if payload[0] == 0x30 {
return &FmpChunk{
Type: FMP_CHUNK_PATH_PUSH,
Value: payload[1 : 1+3],
Length: 4,
}, nil
}
if payload[0] == 0x38 {
chunk.Type = FMP_CHUNK_PATH_PUSH
chunk.Value = payload[1 : 1+1]
chunk.Length = 2
case 0x23:
chunk.Type = FMP_CHUNK_SIMPLE_DATA
chunk.Value = payload[1 : 1+1]
chunk.Length = 2
case 0x28:
chunk.Type = FMP_CHUNK_PATH_PUSH
chunk.Value = payload[1 : 1+2]
chunk.Length = 3
case 0x30:
chunk.Type = FMP_CHUNK_PATH_PUSH
chunk.Value = payload[1 : 1+3]
chunk.Length = 4
case 0x38:
valueLength := payload[1]
return &FmpChunk{
Type: FMP_CHUNK_PATH_PUSH,
Value: payload[2 : 2+valueLength],
Length: 2 + uint64(valueLength),
}, nil
chunk.Type = FMP_CHUNK_PATH_PUSH
chunk.Value = payload[2 : 2+valueLength]
chunk.Length = 2 + uint64(valueLength)
case 0x3D, 0x40:
chunk.Type = FMP_CHUNK_PATH_POP
chunk.Length = 1
case 0x80:
chunk.Type = FMP_CHUNK_NOOP
chunk.Length = 1
default:
return nil, ErrBadChunk
}
// Path pop
if payload[0] == 0x3D || payload[0] == 0x40 {
return &FmpChunk{
Type: FMP_CHUNK_PATH_POP,
Length: 1,
}, nil
}
// No-op
if payload[0] == 0x80 {
return &FmpChunk{
Type: FMP_CHUNK_NOOP,
Length: 1,
}, nil
}
return nil, ErrBadChunk
return chunk, nil
}

9
fmp/fmp_file.go
View File

@ -89,6 +89,14 @@ func OpenFile(path string) (*FmpFile, error) {
case FMP_CHUNK_NOOP:
// noop
}
if chunk.Delayed {
if len(currentPath) == 0 {
println("warning: delayed pop without path")
} else {
currentPath = currentPath[:len(currentPath)-1]
}
}
}
ctx.currentSectorID = sector.NextID
@ -129,6 +137,7 @@ func (ctx *FmpFile) readHeader() error {
}
func (ctx *FmpFile) readSector() (*FmpSector, error) {
println("------- Reading sector", ctx.currentSectorID)
buf := make([]byte, sectorHeaderSize)
n, err := ctx.stream.Read(buf)

11
fmp/fmp_type.go
View File

@ -31,11 +31,12 @@ type FmpSector struct {
}
type FmpChunk struct {
Type FmpChunkType
Length uint64
Key uint64 // If Type == FMP_CHUNK_SHORT_KEY_VALUE or FMP_CHUNK_LONG_KEY_VALUE
Index uint64 // Segment index, if Type == FMP_CHUNK_SEGMENTED_DATA
Value []byte
Type FmpChunkType
Length uint64
Key uint64 // If Type == FMP_CHUNK_SHORT_KEY_VALUE or FMP_CHUNK_LONG_KEY_VALUE
Index uint64 // Segment index, if Type == FMP_CHUNK_SEGMENTED_DATA
Value []byte
Delayed bool
}
type FmpDict map[uint64]*FmpDictEntry