325 lines
7.1 KiB
C
325 lines
7.1 KiB
C
/* xdelta 3 - delta compression tools and library
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* Copyright (C) 2002, 2003, 2006, 2007, 2013. Joshua P. MacDonald
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#ifndef _XDELTA3_SECOND_H_
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#define _XDELTA3_SECOND_H_
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static inline void xd3_bit_state_encode_init (bit_state *bits)
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{
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bits->cur_byte = 0;
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bits->cur_mask = 1;
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}
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static inline int xd3_decode_bits (xd3_stream *stream,
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bit_state *bits,
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const uint8_t **input,
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const uint8_t *input_max,
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usize_t nbits,
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usize_t *valuep)
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{
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usize_t value = 0;
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usize_t vmask = 1 << nbits;
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if (bits->cur_mask == 0x100) { goto next_byte; }
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for (;;)
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{
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do
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{
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vmask >>= 1;
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if (bits->cur_byte & bits->cur_mask)
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{
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value |= vmask;
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}
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bits->cur_mask <<= 1;
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if (vmask == 1) { goto done; }
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}
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while (bits->cur_mask != 0x100);
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next_byte:
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if (*input == input_max)
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{
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stream->msg = "secondary decoder end of input";
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return XD3_INTERNAL;
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}
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bits->cur_byte = *(*input)++;
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bits->cur_mask = 1;
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}
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done:
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IF_DEBUG2 (DP(RINT "(d) %u ", value));
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(*valuep) = value;
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return 0;
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}
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#if REGRESSION_TEST
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/* There may be extra bits at the end of secondary decompression, this macro
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* checks for non-zero bits. This is overly strict, but helps pass the
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* single-bit-error regression test. */
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static int
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xd3_test_clean_bits (xd3_stream *stream, bit_state *bits)
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{
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for (; bits->cur_mask != 0x100; bits->cur_mask <<= 1)
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{
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if (bits->cur_byte & bits->cur_mask)
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{
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stream->msg = "secondary decoder garbage";
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return XD3_INTERNAL;
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}
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}
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return 0;
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}
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#endif
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static int
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xd3_get_secondary (xd3_stream *stream, xd3_sec_stream **sec_streamp,
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int is_encode)
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{
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if (*sec_streamp == NULL)
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{
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int ret;
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if ((*sec_streamp = stream->sec_type->alloc (stream)) == NULL)
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{
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stream->msg = "error initializing secondary stream";
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return XD3_INVALID;
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}
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if ((ret = stream->sec_type->init (stream, *sec_streamp, is_encode)) != 0)
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{
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return ret;
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}
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}
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return 0;
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}
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static int
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xd3_decode_secondary (xd3_stream *stream,
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xd3_desect *sect,
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xd3_sec_stream **sec_streamp)
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{
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uint32_t dec_size;
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uint8_t *out_used;
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int ret;
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if ((ret = xd3_get_secondary (stream, sec_streamp, 0)) != 0)
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{
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return ret;
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}
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/* Decode the size, allocate the buffer. */
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if ((ret = xd3_read_size (stream, & sect->buf,
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sect->buf_max, & dec_size)) ||
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(ret = xd3_decode_allocate (stream, dec_size,
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& sect->copied2, & sect->alloc2)))
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{
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return ret;
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}
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if (dec_size == 0)
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{
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stream->msg = "secondary decoder invalid output size";
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return XD3_INVALID_INPUT;
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}
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out_used = sect->copied2;
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if ((ret = stream->sec_type->decode (stream, *sec_streamp,
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& sect->buf, sect->buf_max,
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& out_used, out_used + dec_size)))
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{
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return ret;
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}
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if (sect->buf != sect->buf_max)
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{
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stream->msg = "secondary decoder finished with unused input";
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return XD3_INTERNAL;
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}
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if (out_used != sect->copied2 + dec_size)
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{
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stream->msg = "secondary decoder short output";
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return XD3_INTERNAL;
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}
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sect->buf = sect->copied2;
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sect->buf_max = sect->copied2 + dec_size;
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sect->size = dec_size;
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return 0;
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}
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#if XD3_ENCODER
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static inline int xd3_encode_bit (xd3_stream *stream,
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xd3_output **output,
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bit_state *bits,
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usize_t bit)
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{
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int ret;
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if (bit)
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{
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bits->cur_byte |= bits->cur_mask;
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}
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/* OPT: Might help to buffer more than 8 bits at once. */
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if (bits->cur_mask == 0x80)
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{
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if ((ret = xd3_emit_byte (stream, output, bits->cur_byte)) != 0)
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{
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return ret;
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}
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bits->cur_mask = 1;
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bits->cur_byte = 0;
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}
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else
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{
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bits->cur_mask <<= 1;
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}
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return 0;
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}
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static inline int xd3_flush_bits (xd3_stream *stream,
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xd3_output **output,
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bit_state *bits)
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{
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return (bits->cur_mask == 1) ? 0 :
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xd3_emit_byte (stream, output, bits->cur_byte);
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}
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static inline int xd3_encode_bits (xd3_stream *stream,
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xd3_output **output,
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bit_state *bits,
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usize_t nbits,
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usize_t value)
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{
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int ret;
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usize_t mask = 1 << nbits;
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XD3_ASSERT (nbits > 0);
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XD3_ASSERT (nbits < sizeof (usize_t) * 8);
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XD3_ASSERT (value < mask);
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do
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{
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mask >>= 1;
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if ((ret = xd3_encode_bit (stream, output, bits, value & mask)))
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{
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return ret;
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}
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}
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while (mask != 1);
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IF_DEBUG2 (DP(RINT "(e) %u ", value));
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return 0;
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}
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static int
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xd3_encode_secondary (xd3_stream *stream,
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xd3_output **head,
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xd3_output **tail,
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xd3_sec_stream **sec_streamp,
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xd3_sec_cfg *cfg,
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int *did_it)
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{
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xd3_output *tmp_head;
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xd3_output *tmp_tail;
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usize_t comp_size;
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usize_t orig_size;
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int ret;
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orig_size = xd3_sizeof_output (*head);
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if (orig_size < SECONDARY_MIN_INPUT) { return 0; }
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if ((ret = xd3_get_secondary (stream, sec_streamp, 1)) != 0)
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{
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return ret;
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}
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tmp_head = xd3_alloc_output (stream, NULL);
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/* Encode the size, encode the data. Encoding the size makes it
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* simpler, but is a little gross. Should not need the entire
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* section in contiguous memory, but it is much easier this way. */
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if ((ret = xd3_emit_size (stream, & tmp_head, orig_size)) ||
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(ret = stream->sec_type->encode (stream, *sec_streamp, *head,
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tmp_head, cfg)))
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{
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goto getout;
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}
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/* If the secondary compressor determines it's no good, it returns
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* XD3_NOSECOND. */
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/* Setup tmp_tail, comp_size */
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tmp_tail = tmp_head;
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comp_size = tmp_head->next;
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while (tmp_tail->next_page != NULL)
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{
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tmp_tail = tmp_tail->next_page;
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comp_size += tmp_tail->next;
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}
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XD3_ASSERT (comp_size == xd3_sizeof_output (tmp_head));
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XD3_ASSERT (tmp_tail != NULL);
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if (comp_size < (orig_size - SECONDARY_MIN_SAVINGS) || cfg->inefficient)
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{
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if (comp_size < orig_size)
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{
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IF_DEBUG1(DP(RINT "[encode_secondary] saved %u bytes: %u -> %u (%0.2f%%)\n",
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orig_size - comp_size, orig_size, comp_size,
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100.0 * (double) comp_size / (double) orig_size));
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}
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xd3_free_output (stream, *head);
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*head = tmp_head;
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*tail = tmp_tail;
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*did_it = 1;
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}
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else
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{
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getout:
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if (ret == XD3_NOSECOND) { ret = 0; }
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xd3_free_output (stream, tmp_head);
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}
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return ret;
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}
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#endif /* XD3_ENCODER */
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#endif /* _XDELTA3_SECOND_H_ */
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