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Diffstat (limited to '')
| -rw-r--r-- | src/liblzma/common/microlzma_encoder.c | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/src/liblzma/common/microlzma_encoder.c b/src/liblzma/common/microlzma_encoder.c new file mode 100644 index 0000000..a787ca2 --- /dev/null +++ b/src/liblzma/common/microlzma_encoder.c @@ -0,0 +1,141 @@ +/////////////////////////////////////////////////////////////////////////////// +// +/// \file microlzma_encoder.c +/// \brief Encode into MicroLZMA format +// +// Author: Lasse Collin +// +// This file has been put into the public domain. +// You can do whatever you want with this file. +// +/////////////////////////////////////////////////////////////////////////////// + +#include "lzma_encoder.h" + + +typedef struct { + /// LZMA1 encoder + lzma_next_coder lzma; + + /// LZMA properties byte (lc/lp/pb) + uint8_t props; +} lzma_microlzma_coder; + + +static lzma_ret +microlzma_encode(void *coder_ptr, const lzma_allocator *allocator, + const uint8_t *restrict in, size_t *restrict in_pos, + size_t in_size, uint8_t *restrict out, + size_t *restrict out_pos, size_t out_size, lzma_action action) +{ + lzma_microlzma_coder *coder = coder_ptr; + + // Remember *out_pos so that we can overwrite the first byte with + // the LZMA properties byte. + const size_t out_start = *out_pos; + + // Remember *in_pos so that we can set it based on how many + // uncompressed bytes were actually encoded. + const size_t in_start = *in_pos; + + // Set the output size limit based on the available output space. + // We know that the encoder supports set_out_limit() so + // LZMA_OPTIONS_ERROR isn't possible. LZMA_BUF_ERROR is possible + // but lzma_code() has an assertion to not allow it to be returned + // from here and I don't want to change that for now, so + // LZMA_BUF_ERROR becomes LZMA_PROG_ERROR. + uint64_t uncomp_size; + if (coder->lzma.set_out_limit(coder->lzma.coder, + &uncomp_size, out_size - *out_pos) != LZMA_OK) + return LZMA_PROG_ERROR; + + // set_out_limit fails if this isn't true. + assert(out_size - *out_pos >= 6); + + // Encode as much as possible. + const lzma_ret ret = coder->lzma.code(coder->lzma.coder, allocator, + in, in_pos, in_size, out, out_pos, out_size, action); + + if (ret != LZMA_STREAM_END) { + if (ret == LZMA_OK) { + assert(0); + return LZMA_PROG_ERROR; + } + + return ret; + } + + // The first output byte is bitwise-negation of the properties byte. + // We know that there is space for this byte because set_out_limit + // and the actual encoding succeeded. + out[out_start] = (uint8_t)(~coder->props); + + // The LZMA encoder likely read more input than it was able to encode. + // Set *in_pos based on uncomp_size. + assert(uncomp_size <= in_size - in_start); + *in_pos = in_start + (size_t)(uncomp_size); + + return ret; +} + + +static void +microlzma_encoder_end(void *coder_ptr, const lzma_allocator *allocator) +{ + lzma_microlzma_coder *coder = coder_ptr; + lzma_next_end(&coder->lzma, allocator); + lzma_free(coder, allocator); + return; +} + + +static lzma_ret +microlzma_encoder_init(lzma_next_coder *next, const lzma_allocator *allocator, + const lzma_options_lzma *options) +{ + lzma_next_coder_init(µlzma_encoder_init, next, allocator); + + lzma_microlzma_coder *coder = next->coder; + + if (coder == NULL) { + coder = lzma_alloc(sizeof(lzma_microlzma_coder), allocator); + if (coder == NULL) + return LZMA_MEM_ERROR; + + next->coder = coder; + next->code = µlzma_encode; + next->end = µlzma_encoder_end; + + coder->lzma = LZMA_NEXT_CODER_INIT; + } + + // Encode the properties byte. Bitwise-negation of it will be the + // first output byte. + if (lzma_lzma_lclppb_encode(options, &coder->props)) + return LZMA_OPTIONS_ERROR; + + // Initialize the LZMA encoder. + const lzma_filter_info filters[2] = { + { + .id = LZMA_FILTER_LZMA1, + .init = &lzma_lzma_encoder_init, + .options = (void *)(options), + }, { + .init = NULL, + } + }; + + return lzma_next_filter_init(&coder->lzma, allocator, filters); +} + + +extern LZMA_API(lzma_ret) +lzma_microlzma_encoder(lzma_stream *strm, const lzma_options_lzma *options) +{ + lzma_next_strm_init(microlzma_encoder_init, strm, options); + + strm->internal->supported_actions[LZMA_FINISH] = true; + + return LZMA_OK; + +} |