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70 lines
1.9 KiB
70 lines
1.9 KiB
10 years ago
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///////////////////////////////////////////////////////////////////////////////
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//
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/// \file vli_encoder.c
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/// \brief Encodes variable-length integers
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//
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// Author: Lasse Collin
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//
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// This file has been put into the public domain.
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// You can do whatever you want with this file.
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//
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///////////////////////////////////////////////////////////////////////////////
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#include "common.h"
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extern LZMA_API(lzma_ret)
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lzma_vli_encode(lzma_vli vli, size_t *vli_pos,
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uint8_t *LZMA_RESTRICT out, size_t *LZMA_RESTRICT out_pos,
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size_t out_size)
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{
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// If we haven't been given vli_pos, work in single-call mode.
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size_t vli_pos_internal = 0;
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if (vli_pos == NULL) {
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vli_pos = &vli_pos_internal;
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// In single-call mode, we expect that the caller has
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// reserved enough output space.
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if (*out_pos >= out_size)
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return LZMA_PROG_ERROR;
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} else {
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// This never happens when we are called by liblzma, but
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// may happen if called directly from an application.
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if (*out_pos >= out_size)
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return LZMA_BUF_ERROR;
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}
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// Validate the arguments.
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if (*vli_pos >= LZMA_VLI_BYTES_MAX || vli > LZMA_VLI_MAX)
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return LZMA_PROG_ERROR;
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// Shift vli so that the next bits to encode are the lowest. In
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// single-call mode this never changes vli since *vli_pos is zero.
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vli >>= *vli_pos * 7;
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// Write the non-last bytes in a loop.
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while (vli >= 0x80) {
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// We don't need *vli_pos during this function call anymore,
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// but update it here so that it is ready if we need to
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// return before the whole integer has been decoded.
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++*vli_pos;
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assert(*vli_pos < LZMA_VLI_BYTES_MAX);
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// Write the next byte.
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out[*out_pos] = (uint8_t)(vli) | 0x80;
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vli >>= 7;
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if (++*out_pos == out_size)
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return vli_pos == &vli_pos_internal
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? LZMA_PROG_ERROR : LZMA_OK;
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}
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// Write the last byte.
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out[*out_pos] = (uint8_t)(vli);
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++*out_pos;
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++*vli_pos;
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return vli_pos == &vli_pos_internal ? LZMA_OK : LZMA_STREAM_END;
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}
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