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Diffstat (limited to 'serializer.c')
| -rw-r--r-- | serializer.c | 326 |
1 files changed, 326 insertions, 0 deletions
diff --git a/serializer.c b/serializer.c new file mode 100644 index 0000000..287ee22 --- /dev/null +++ b/serializer.c @@ -0,0 +1,326 @@ +/* + Copyright 2020 Xavier Del Campo Romero + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. +*/ + +#include "serializer.h" +#include <stddef.h> +#include <stdbool.h> +#include <string.h> +#include <stdint.h> + +static bool little_endian(void) +{ + return (const union {char c; int b;}){.c = 1}.b; +} + +enum serializer_err serialize(const char *format, void *dst, size_t sz, const void *src, const size_t src_sz) +{ + if (!format || !dst || !sz || !src) + { + return SERIALIZER_ERR_INVALID_ARG; + } + + return SERIALIZER_OK; +} + +enum token +{ + TOKEN_8BIT, + TOKEN_LE16BIT, + TOKEN_BE16BIT, + TOKEN_LE32BIT, + TOKEN_BE32BIT, + TOKEN_NOT_READY, + TOKEN_ERROR +}; + +enum state +{ + ENDIAN_SPECIFIER_OR_8BIT_OR_SLASH, + CHARACTER_E, + MULTI_BYTE_NUM +}; + +enum endianness +{ + ENDIANESS_UNKNOWN, + LITTLE_ENDIAN, + BIG_ENDIAN +}; + +static enum token get_spec_8bit(const char c, enum state *const state, enum endianness *const endianness) +{ + switch (c) + { + case '/': + return TOKEN_NOT_READY; + + case '1': + return TOKEN_8BIT; + + case 'l': + *state = CHARACTER_E; + *endianness = LITTLE_ENDIAN; + return TOKEN_NOT_READY; + + case 'b': + *state = CHARACTER_E; + *endianness = BIG_ENDIAN; + return TOKEN_NOT_READY; + + default: + break; + } + + return TOKEN_ERROR; +} + +static enum token get_ech(const char c, enum state *const state, enum endianness *const endianness) +{ + if (c == 'e') + { + *state = MULTI_BYTE_NUM; + return TOKEN_NOT_READY; + } + + return TOKEN_ERROR; +} + +static enum token get_multibyte(const char c, enum state *const state, enum endianness *const endianness) +{ + switch (c) + { + case '2': + + switch (*endianness) + { + case LITTLE_ENDIAN: + return TOKEN_LE16BIT; + + case BIG_ENDIAN: + return TOKEN_BE16BIT; + + default: + break; + } + + break; + + case '4': + + switch (*endianness) + { + case LITTLE_ENDIAN: + return TOKEN_LE32BIT; + + case BIG_ENDIAN: + return TOKEN_BE32BIT; + + default: + break; + } + + break; + + default: + break; + } + + return TOKEN_ERROR; +} + +static enum token get_token(const char c, enum state *const state, enum endianness *const endianness) +{ + static enum token (*const get[])(char c, enum state *state, enum endianness *endianness) = + { + [ENDIAN_SPECIFIER_OR_8BIT_OR_SLASH] = get_spec_8bit, + [CHARACTER_E] = get_ech, + [MULTI_BYTE_NUM] = get_multibyte + }; + + return get[*state](c, state, endianness); +} + +static void read8(void *const dst, const void *const src) +{ + *(uint8_t *)dst = *(const uint8_t *)src; +} + +static size_t swap32(void *dst, const void *const src) +{ + *(uint8_t *)dst++ = *((const uint8_t *)src + 3); + *(uint8_t *)dst++ = *((const uint8_t *)src + 2); + *(uint8_t *)dst++ = *((const uint8_t *)src + 1); + *(uint8_t *)dst = *(const uint8_t *)src; +} + +static void readbe32(void *const dst, const void *const src) +{ + enum + { + SZ = sizeof (uint32_t) + }; + + if (little_endian()) + { + swap32(dst, src); + } + else + { + memmove(dst, src, SZ); + } +} + +static void readle32(void *const dst, const void *const src) +{ + enum + { + SZ = sizeof (uint32_t) + }; + + if (little_endian()) + { + memmove(dst, src, SZ); + } + else + { + swap32(dst, src); + } +} + +static size_t swap16(void *dst, const void *const src) +{ + *(uint8_t *)dst++ = *((const uint8_t *)src + 1); + *(uint8_t *)dst = *(const uint8_t *)src; +} + +static void readbe16(void *const dst, const void *const src) +{ + enum + { + SZ = sizeof (uint16_t) + }; + + if (little_endian()) + { + swap16(dst, src); + } + else + { + memmove(dst, src, SZ); + } +} + +static void readle16(void *const dst, const void *const src) +{ + enum + { + SZ = sizeof (uint16_t) + }; + + if (little_endian()) + { + memmove(dst, src, SZ); + } + else + { + swap16(dst, src); + } +} + +enum serializer_err deserialize(const char *format, + void *const dst, + const size_t sz, + const void *const src, + const size_t src_sz) +{ + if (!format || !dst || !sz || !src) + { + return SERIALIZER_ERR_INVALID_ARG; + } + else + { + enum state state = 0; + enum endianness endianness = ENDIANESS_UNKNOWN; + char c; + size_t in_sz = 0, out_sz = 0; + + while (c = *format) + { + const enum token token = get_token(c, &state, &endianness); + + switch (token) + { + default: + { + static const size_t sizes[] = + { + [TOKEN_8BIT] = sizeof (uint8_t), + [TOKEN_LE16BIT] = sizeof (uint16_t), + [TOKEN_BE16BIT] = sizeof (uint16_t), + [TOKEN_LE32BIT] = sizeof (uint32_t), + [TOKEN_BE32BIT] = sizeof (uint32_t) + }; + + const size_t st = sizes[token]; + + static void (*const read[])(void *dst, const void *src) = + { + [TOKEN_8BIT] = read8, + [TOKEN_LE16BIT] = readle16, + [TOKEN_BE16BIT] = readbe16, + [TOKEN_LE32BIT] = readle32, + [TOKEN_BE32BIT] = readbe32 + }; + + const size_t padding = out_sz % st; + + if (padding) + { + out_sz += st - padding; + } + + if (in_sz + st > src_sz) + return SERIALIZER_ERR_IN_OVERFLOW; + else if (out_sz + st <= sz) + { + read[token]((uint8_t *)dst + out_sz, (const uint8_t *)src + in_sz); + in_sz += st; + out_sz += st; + state = 0; + } + else + return SERIALIZER_ERR_OUT_OVERFLOW; + } + break; + + case TOKEN_ERROR: + return SERIALIZER_ERR_FORMAT; + + case TOKEN_NOT_READY: + break; + } + + format++; + } + + if (!out_sz) + { + return SERIALIZER_ERR_FORMAT; + } + } + + return SERIALIZER_OK; +} |