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Diffstat (limited to 'subprojects/exess/src/hex.c')
-rw-r--r-- | subprojects/exess/src/hex.c | 131 |
1 files changed, 131 insertions, 0 deletions
diff --git a/subprojects/exess/src/hex.c b/subprojects/exess/src/hex.c new file mode 100644 index 00000000..bd9de4d6 --- /dev/null +++ b/subprojects/exess/src/hex.c @@ -0,0 +1,131 @@ +/* + Copyright 2011-2021 David Robillard <d@drobilla.net> + + Permission to use, copy, modify, and/or distribute this software for any + purpose with or without fee is hereby granted, provided that the above + copyright notice and this permission notice appear in all copies. + + THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. +*/ + +#include "read_utils.h" +#include "string_utils.h" +#include "write_utils.h" + +#include "exess/exess.h" + +#include <stdint.h> +#include <string.h> + +/// Hex encoding table +static const char hex_map[] = "0123456789ABCDEF"; + +static inline uint8_t +decode_nibble(const char c) +{ + if (is_digit(c)) { + return (uint8_t)(c - '0'); + } + + if (c >= 'A' && c <= 'F') { + return (uint8_t)(10 + c - 'A'); + } + + if (c >= 'a' && c <= 'f') { + return (uint8_t)(10 + c - 'a'); + } + + return UINT8_MAX; +} + +static char +next_char(const char* const str, size_t* const i) +{ + *i += skip_whitespace(str + *i); + + return str[*i]; +} + +size_t +exess_hex_decoded_size(const size_t length) +{ + return length / 2; +} + +ExessResult +exess_read_hex(ExessBlob* const out, const char* const str) +{ + uint8_t* const uout = (uint8_t*)out->data; + size_t i = 0u; + size_t o = 0u; + + while (str[i]) { + const char hi_char = next_char(str, &i); + if (!hi_char) { + break; + } + + ++i; + + const uint8_t hi = decode_nibble(hi_char); + if (hi == UINT8_MAX) { + return result(EXESS_EXPECTED_HEX, i); + } + + const char lo_char = next_char(str, &i); + if (!lo_char) { + return result(EXESS_EXPECTED_HEX, i); + } + + ++i; + + const uint8_t lo = decode_nibble(lo_char); + if (lo == UINT8_MAX) { + return result(EXESS_EXPECTED_HEX, i); + } + + if (o >= out->size) { + return result(EXESS_NO_SPACE, i); + } + + uout[o++] = (uint8_t)(hi << 4u) | lo; + } + + out->size = o; + return result(EXESS_SUCCESS, i); +} + +ExessResult +exess_write_hex(const size_t data_size, + const void* const data, + const size_t buf_size, + char* const buf) +{ + const size_t length = 2 * data_size; + if (!buf) { + return result(EXESS_SUCCESS, length); + } + + if (buf_size < length + 1) { + return result(EXESS_NO_SPACE, 0); + } + + const uint8_t* const in = (const uint8_t*)data; + size_t o = 0u; + + for (size_t i = 0; i < data_size; ++i) { + const uint8_t hi = (in[i] & 0xF0u) >> 4u; + const uint8_t lo = (in[i] & 0x0Fu); + + buf[o++] = hex_map[hi]; + buf[o++] = hex_map[lo]; + } + + return end_write(EXESS_SUCCESS, buf_size, buf, o); +} |