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2 changed files with 119 additions and 41 deletions

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@ -6,64 +6,142 @@ import "slices"
// encoding and decoding functions must not make any allocations // encoding and decoding functions must not make any allocations
func DecodeArray(data []byte, itemLength int) iter.Seq[[]byte] { // ArrayPushFunc adds an item to an array that is being encoded.
type ArrayPushFunc func(value []byte) (n int, err error)
// ArrayPullFunc gets the next item of an array that is being decoded.
type ArrayPullFunc func() (value []byte, n int, err error)
// DecodePASTA decodes a packed single-type array.
func DecodePASTA(data []byte, itemLength int) ArrayPullFunc {
n := 0
return func() (value []byte, n_ int, err error) {
if n > len(data) - itemLength {
return nil, 0, fmt.Errorf("decoding PASTA: %w", ErrWrongBufferLength)
}
value = data[n:n + itemLength]
n += itemLength
return value, itemLength, nil
}
}
// DecodePASTAIter decodes a packed single-type array and returns it as an
// iterator.
func DecodePASTAIter(data []byte, itemLength int) iter.Seq[[]byte] {
return slices.Chunk(data, itemLength) return slices.Chunk(data, itemLength)
} }
func EncodeArray(data []byte, items ...[]byte) (n int, err error) { // EncodePASTA encodes a packed single-type array.
for _, item := range items { func EncodePASTA(data []byte, itemLength int) ArrayPushFunc {
if n >= len(data) { return n, ErrWrongBufferLength } n := 0
copy(data[n:], item) return func(value []byte) (n_ int, err error) {
n += len(item) if n > len(data) - itemLength {
return 0, fmt.Errorf("encoding PASTA: %w", ErrWrongBufferLength)
}
copy(data[n:], value)
n += itemLength
return itemLength, nil
} }
return n, nil
} }
func ArraySize(length, itemLength int) int { // PASTASize returns the size of a packed single-type array.
func PASTASize(length, itemLength int) int {
return length * itemLength return length * itemLength
} }
// DecodeStringArray decodes a packed string array from the given data. // DecodeVILA encodes a variable item length array.
func DecodeStringArray[T String](data []byte) (result []T, n int, err error) { func DecodeVILA(data []byte) ArrayPullFunc {
for len(data) > 0 { n := 0
if len(data) < 2 { return nil, n, fmt.Errorf("decoding []string: %w", ErrWrongBufferLength) } return func() (value []byte, n_ int, err error) {
itemSize16, nn, _ := DecodeI16[uint16](data[:2]) if n >= len(data) { return nil, n_, fmt.Errorf("decoding VILA: %w", ErrWrongBufferLength) }
itemSize := int(itemSize16) length, nn, err := DecodeGBEU[uint](data[n:])
n += nn n += nn
data = data[nn:] n_ += nn
if len(data) < itemSize { return nil, n, fmt.Errorf("decoding []string: %w", ErrWrongBufferLength) } if err != nil { return nil, n_, err }
result = append(result, T(data[:itemSize]))
data = data[itemSize:] if n > len(data) - int(length) {
n += itemSize return nil, n_, fmt.Errorf("decoding VILA: %w", ErrWrongBufferLength)
}
value = data[n:n + int(length)]
n += int(length)
n_ += int(length)
return value, int(length), nil
}
}
// DecodeVILAIter decodes a variable item length array and returns it as an
// iterator.
func DecodeVILAIter(data []byte) iter.Seq[[]byte] {
return func(yield func([]byte) bool) {
pull := DecodeVILA(data)
for {
value, _, err := pull()
if err != nil { return }
if !yield(value) { return }
}
}
}
// EncodeVILA encodes a variable item length array.
func EncodeVILA(data []byte) ArrayPushFunc {
n := 0
return func(value []byte) (n_ int, err error) {
if n >= len(data) { return n_, fmt.Errorf("encoding VILA: %w", ErrWrongBufferLength) }
nn, err := EncodeGBEU(data[n:], uint(len(value)))
n += nn
n_ += nn
if err != nil { return n, err }
if n >= len(data) { return n_, fmt.Errorf("encoding VILA: %w", ErrWrongBufferLength) }
nn = copy(data[n:], value)
n += nn
n_ += nn
if nn != len(value) { return n_, fmt.Errorf("encoding VILA: %w", ErrWrongBufferLength) }
return n_, err
}
}
// VILASize returns the size of a variable item length array.
func VILASize(items ...[]byte) int {
size := 0
for _, item := range items {
size += GBEUSize[uint](uint(len(item)))
size += len(item)
}
return size
}
// DecodeStringArray decodes a VILA string array from the given data.
func DecodeStringArray[T String](data []byte) (result []T, n int, err error) {
pull := DecodeVILA(data)
for {
item, nn, err := pull()
n += nn
if err != nil { return nil, n, err }
result = append(result, T(item))
} }
return result, n, nil return result, n, nil
} }
// EncodeStringArray encodes a packed string array into the given buffer. // EncodeStringArray encodes a VILA string array into the given buffer.
func EncodeStringArray[T String](buffer []byte, value []T) (n int, err error) { func EncodeStringArray[T String](buffer []byte, value []T) (n int, err error) {
push := EncodeVILA(buffer)
for _, item := range value { for _, item := range value {
length, err := StringSize(item) nn, err := push([]byte(item))
n += nn
if err != nil { return n, err } if err != nil { return n, err }
if len(buffer) < 2 + length { return n, fmt.Errorf("encoding []string: %w", ErrWrongBufferLength) }
EncodeI16(buffer[:2], uint16(length))
buffer = buffer[2:]
copy(buffer, item)
buffer = buffer[length:]
n += 2 + length
} }
if len(buffer) > 0 { return n, fmt.Errorf("encoding []string: %w", ErrWrongBufferLength) }
return n, nil return n, nil
} }
// StringArraySize returns the size of a packed string array. Returns 0 and an // StringArraySize returns the size of a VILA string array.
// error if the size is too large. func StringArraySize[T String](value []T) int {
func StringArraySize[T String](value []T) (int, error) { size := 0
total := 0
for _, item := range value { for _, item := range value {
total += 2 + len(item) size += GBEUSize[uint](uint(len(item)))
size += len(item)
} }
if total > dataMaxSize { return 0, ErrDataTooLarge } return size
return total, nil
} }
// DecodeI8Array decodes a packed array of 8 bit integers from the given data. // DecodeI8Array decodes a packed array of 8 bit integers from the given data.

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@ -28,10 +28,10 @@ type Int16 interface { ~uint16 | ~int16 }
type Int32 interface { ~uint32 | ~int32 } type Int32 interface { ~uint32 | ~int32 }
// Int64 is any 64-bit integer. // Int64 is any 64-bit integer.
type Int64 interface { ~uint64 | ~int64 } type Int64 interface { ~uint64 | ~int64 }
// UInt is any unsigned integer. // Uint is any unsigned integer.
type UInt interface { ~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 } type Uint interface { ~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 }
// String is any string. // String is any string.
type String interface { ~string } type String interface { ~string | ~[]uint8 }
// DecodeI8 decodes an 8 bit integer from the given data. // DecodeI8 decodes an 8 bit integer from the given data.
func DecodeI8[T Int8](data []byte) (value T, n int, err error) { func DecodeI8[T Int8](data []byte) (value T, n int, err error) {
@ -107,7 +107,7 @@ func EncodeI64[T Int64](buffer []byte, value T) (n int, err error) {
} }
// DecodeGBEU decodes an 8 to 64 bit growing integer into the given buffer. // DecodeGBEU decodes an 8 to 64 bit growing integer into the given buffer.
func DecodeGBEU[T UInt](data []byte) (value T, n int, err error) { func DecodeGBEU[T Uint](data []byte) (value T, n int, err error) {
var fullValue uint64 var fullValue uint64
for _, chunk := range data { for _, chunk := range data {
fullValue *= 0x80 fullValue *= 0x80
@ -122,7 +122,7 @@ func DecodeGBEU[T UInt](data []byte) (value T, n int, err error) {
} }
// EncodeGBEU encodes an 8 to 64 bit growing integer into a given buffer. // EncodeGBEU encodes an 8 to 64 bit growing integer into a given buffer.
func EncodeGBEU[T UInt] (buffer []byte, value T) (n int, err error) { func EncodeGBEU[T Uint] (buffer []byte, value T) (n int, err error) {
window := (GBEUSize(value) - 1) * 7 window := (GBEUSize(value) - 1) * 7
index := 0 index := 0
@ -142,7 +142,7 @@ func EncodeGBEU[T UInt] (buffer []byte, value T) (n int, err error) {
} }
// GBEUSize returns the size (in octets) of a GBEU integer. // GBEUSize returns the size (in octets) of a GBEU integer.
func GBEUSize[T UInt] (value T) int { func GBEUSize[T Uint] (value T) int {
length := 0 length := 0
for { for {
value >>= 7 value >>= 7