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// Encoding and decoding of hex-encoded binary, e.g. `0x23` -> `#`.
package encoding_hex
import "base:runtime"
import "core:io"
import "core:strings"
/*
Encodes a byte slice into a lowercase hex sequence
*Allocates Using Provided Allocator*
Inputs:
- src: The `[]byte` to be hex-encoded
- allocator: (default: context.allocator)
- loc: The caller location for debugging purposes (default: #caller_location)
Returns:
- res: The hex-encoded result
- err: An optional allocator error if one occured, `.None` otherwise
*/
encode :: proc(src: []byte, allocator := context.allocator, loc := #caller_location) -> (res: []byte, err: runtime.Allocator_Error) #optional_allocator_error {
res, err = make([]byte, len(src) * 2, allocator, loc)
#no_bounds_check for i, j := 0, 0; i < len(src); i += 1 {
v := src[i]
res[j] = LOWER[v>>4]
res[j+1] = LOWER[v&0x0f]
j += 2
}
return
}
/*
Encodes a byte slice as a lowercase hex sequence into an `io.Writer`
Inputs:
- dst: The `io.Writer` to encode into
- src: The `[]byte` to be hex-encoded
Returns:
- err: An `io.Error` if one occured, `.None` otherwise
*/
encode_into_writer :: proc(dst: io.Writer, src: []byte) -> (err: io.Error) {
for v in src {
io.write(dst, {LOWER[v>>4], LOWER[v&0x0f]}) or_return
}
return
}
/*
Encodes a byte slice into an uppercase hex sequence
*Allocates Using Provided Allocator*
Inputs:
- src: The `[]byte` to be hex-encoded
- allocator: (default: context.allocator)
- loc: The caller location for debugging purposes (default: #caller_location)
Returns:
- res: The hex-encoded result
- err: An optional allocator error if one occured, `.None` otherwise
*/
encode_upper :: proc(src: []byte, allocator := context.allocator, loc := #caller_location) -> (res: []byte, err: runtime.Allocator_Error) #optional_allocator_error {
res, err = make([]byte, len(src) * 2, allocator, loc)
#no_bounds_check for i, j := 0, 0; i < len(src); i += 1 {
v := src[i]
res[j] = UPPER[v>>4]
res[j+1] = UPPER[v&0x0f]
j += 2
}
return
}
/*
Encodes a byte slice as an uppercase hex sequence into an `io.Writer`
Inputs:
- dst: The `io.Writer` to encode into
- src: The `[]byte` to be hex-encoded
Returns:
- err: An `io.Error` if one occured, `.None` otherwise
*/
encode_upper_into_writer :: proc(dst: io.Writer, src: []byte) -> (err: io.Error) {
for v in src {
io.write(dst, {UPPER[v>>4], UPPER[v&0x0f]}) or_return
}
return
}
/*
Decodes a hex sequence into a byte slice
*Allocates Using Provided Allocator*
Inputs:
- dst: The hex sequence decoded into bytes
- src: The `[]byte` to be hex-decoded
- allocator: (default: context.allocator)
- loc: The caller location for debugging purposes (default: #caller_location)
Returns:
- ok: A bool, `true` if decoding succeeded, `false` otherwise
*/
decode :: proc(src: []byte, allocator := context.allocator, loc := #caller_location) -> (dst: []byte, ok: bool) {
if len(src) % 2 == 1 {
return
}
dst = make([]byte, len(src) / 2, allocator, loc)
#no_bounds_check for i, j := 0, 1; j < len(src); j += 2 {
p := src[j-1]
q := src[j]
a := hex_digit(p) or_return
b := hex_digit(q) or_return
dst[i] = (a << 4) | b
i += 1
}
return dst, true
}
/*
Decodes the first byte in a hex sequence to a byte
Inputs:
- str: A hex-encoded `string`, e.g. `"0x23"`
Returns:
- res: The decoded byte, e.g. `'#'`
- ok: A bool, `true` if decoding succeeded, `false` otherwise
*/
decode_sequence :: proc(str: string) -> (res: byte, ok: bool) {
str := str
if strings.has_prefix(str, "0x") || strings.has_prefix(str, "0X") {
str = str[2:]
}
if len(str) != 2 {
return 0, false
}
upper := hex_digit(str[0]) or_return
lower := hex_digit(str[1]) or_return
return upper << 4 | lower, true
}
@(private)
LOWER := [16]byte {
'0', '1', '2', '3',
'4', '5', '6', '7',
'8', '9', 'a', 'b',
'c', 'd', 'e', 'f',
}
@(private)
UPPER := [16]byte {
'0', '1', '2', '3',
'4', '5', '6', '7',
'8', '9', 'A', 'B',
'C', 'D', 'E', 'F',
}
@(private)
hex_digit :: proc(char: byte) -> (u8, bool) {
switch char {
case '0' ..= '9': return char - '0', true
case 'a' ..= 'f': return char - 'a' + 10, true
case 'A' ..= 'F': return char - 'A' + 10, true
case: return 0, false
}
}
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