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encoding/base64: add decode_into, add tests

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This commit is contained in:
Laytan Laats
2023-12-16 21:40:41 +01:00
parent 5533a327eb
commit b6c47e7963
4 changed files with 158 additions and 46 deletions
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139
core/encoding/base64/base64.odin
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@@ -44,21 +44,48 @@ DEC_TABLE := [128]int {
}
encode :: proc(data: []byte, ENC_TBL := ENC_TABLE, allocator := context.allocator) -> (encoded: string, err: mem.Allocator_Error) #optional_allocator_error {
out_length := encoded_length(data)
out_length := encoded_len(data)
if out_length == 0 {
return
}
out: strings.Builder
strings.builder_init(&out, 0, out_length, allocator) or_return
out := strings.builder_make(0, out_length, allocator) or_return
ioerr := encode_into(strings.to_stream(&out), data, ENC_TBL)
assert(ioerr == nil)
assert(ioerr == nil, "string builder should not IO error")
assert(strings.builder_cap(out) == out_length, "buffer resized, `encoded_len` was wrong")
return strings.to_string(out), nil
}
encoded_length :: #force_inline proc(data: []byte) -> int {
encode_into :: proc(w: io.Writer, data: []byte, ENC_TBL := ENC_TABLE) -> io.Error {
length := len(data)
if length == 0 {
return nil
}
c0, c1, c2, block: int
out: [4]byte
for i := 0; i < length; i += 3 {
#no_bounds_check {
c0, c1, c2 = int(data[i]), -1, -1
if i + 1 < length { c1 = int(data[i + 1]) }
if i + 2 < length { c2 = int(data[i + 2]) }
block = (c0 << 16) | (max(c1, 0) << 8) | max(c2, 0)
out[0] = ENC_TBL[block >> 18 & 63]
out[1] = ENC_TBL[block >> 12 & 63]
out[2] = c1 == -1 ? PADDING : ENC_TBL[block >> 6 & 63]
out[3] = c2 == -1 ? PADDING : ENC_TBL[block & 63]
}
io.write_full(w, out[:]) or_return
}
return nil
}
encoded_len :: proc(data: []byte) -> int {
length := len(data)
if length == 0 {
return 0
@@ -67,48 +94,30 @@ encoded_length :: #force_inline proc(data: []byte) -> int {
return ((4 * length / 3) + 3) &~ 3
}
encode_into :: proc(w: io.Writer, data: []byte, ENC_TBL := ENC_TABLE) -> (err: io.Error) #no_bounds_check {
length := len(data)
if length == 0 {
return
}
decode :: proc(data: string, DEC_TBL := DEC_TABLE, allocator := context.allocator) -> (decoded: []byte, err: mem.Allocator_Error) #optional_allocator_error {
out_length := decoded_len(data)
c0, c1, c2, block: int
out := strings.builder_make(0, out_length, allocator) or_return
ioerr := decode_into(strings.to_stream(&out), data, DEC_TBL)
for i, d := 0, 0; i < length; i, d = i + 3, d + 4 {
c0, c1, c2 = int(data[i]), -1, -1
assert(ioerr == nil, "string builder should not IO error")
assert(strings.builder_cap(out) == out_length, "buffer resized, `decoded_len` was wrong")
if i + 1 < length { c1 = int(data[i + 1]) }
if i + 2 < length { c2 = int(data[i + 2]) }
block = (c0 << 16) | (max(c1, 0) << 8) | max(c2, 0)
out: [4]byte
out[0] = ENC_TBL[block >> 18 & 63]
out[1] = ENC_TBL[block >> 12 & 63]
out[2] = c1 == -1 ? PADDING : ENC_TBL[block >> 6 & 63]
out[3] = c2 == -1 ? PADDING : ENC_TBL[block & 63]
#bounds_check { io.write_full(w, out[:]) or_return }
}
return
return out.buf[:], nil
}
decode :: proc(data: string, DEC_TBL := DEC_TABLE, allocator := context.allocator) -> (out: []byte, err: mem.Allocator_Error) #optional_allocator_error {
#no_bounds_check {
length := len(data)
if length == 0 {
return
}
decode_into :: proc(w: io.Writer, data: string, DEC_TBL := DEC_TABLE) -> io.Error {
length := decoded_len(data)
if length == 0 {
return nil
}
pad_count := data[length - 1] == PADDING ? (data[length - 2] == PADDING ? 2 : 1) : 0
out_length := ((length * 6) >> 3) - pad_count
out = make([]byte, out_length, allocator) or_return
c0, c1, c2, c3: int
b0, b1, b2: int
for i, j := 0, 0; i < length; i, j = i + 4, j + 3 {
c0, c1, c2, c3: int
b0, b1, b2: int
buf: [3]byte
i, j: int
for ; j + 3 <= length; i, j = i + 4, j + 3 {
#no_bounds_check {
c0 = DEC_TBL[data[i]]
c1 = DEC_TBL[data[i + 1]]
c2 = DEC_TBL[data[i + 2]]
@@ -118,10 +127,48 @@ decode :: proc(data: string, DEC_TBL := DEC_TABLE, allocator := context.allocato
b1 = (c1 << 4) | (c2 >> 2)
b2 = (c2 << 6) | c3
out[j] = byte(b0)
out[j + 1] = byte(b1)
out[j + 2] = byte(b2)
buf[0] = byte(b0)
buf[1] = byte(b1)
buf[2] = byte(b2)
}
return
io.write_full(w, buf[:]) or_return
}
rest := length - j
if rest > 0 {
#no_bounds_check {
c0 = DEC_TBL[data[i]]
c1 = DEC_TBL[data[i + 1]]
c2 = DEC_TBL[data[i + 2]]
b0 = (c0 << 2) | (c1 >> 4)
b1 = (c1 << 4) | (c2 >> 2)
}
switch rest {
case 1: io.write_byte(w, byte(b0)) or_return
case 2: io.write_full(w, {byte(b0), byte(b1)}) or_return
}
}
return nil
}
decoded_len :: proc(data: string) -> int {
length := len(data)
if length == 0 {
return 0
}
padding: int
if data[length - 1] == PADDING {
if length > 1 && data[length - 2] == PADDING {
padding = 2
} else {
padding = 1
}
}
return ((length * 6) >> 3) - padding
}