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/* xdelta 3 - delta compression tools and library |
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* Copyright (C) 2002, 2003, 2006, 2007. 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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|
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#ifndef _XDELTA3_SECOND_H_ |
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#define _XDELTA3_SECOND_H_ |
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|
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/****************************************************************************************** |
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Secondary compression |
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******************************************************************************************/ |
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|
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#define xd3_sec_data(s) ((s)->sec_stream_d) |
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#define xd3_sec_inst(s) ((s)->sec_stream_i) |
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#define xd3_sec_addr(s) ((s)->sec_stream_a) |
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|
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struct _xd3_sec_type |
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{ |
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int id; |
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const char *name; |
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xd3_secondary_flags flags; |
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|
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/* xd3_sec_stream is opaque to the generic code */ |
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xd3_sec_stream* (*alloc) (xd3_stream *stream); |
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void (*destroy) (xd3_stream *stream, |
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xd3_sec_stream *sec); |
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void (*init) (xd3_sec_stream *sec); |
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int (*decode) (xd3_stream *stream, |
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xd3_sec_stream *sec_stream, |
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const uint8_t **input, |
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const uint8_t *input_end, |
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uint8_t **output, |
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const uint8_t *output_end); |
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#if XD3_ENCODER |
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int (*encode) (xd3_stream *stream, |
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xd3_sec_stream *sec_stream, |
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xd3_output *input, |
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xd3_output *output, |
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xd3_sec_cfg *cfg); |
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#endif |
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}; |
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|
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#define BIT_STATE_ENCODE_INIT { 0, 1 } |
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#define BIT_STATE_DECODE_INIT { 0, 0x100 } |
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|
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typedef struct _bit_state bit_state; |
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struct _bit_state |
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{ |
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usize_t cur_byte; |
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usize_t cur_mask; |
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}; |
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|
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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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|
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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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|
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if (bits->cur_mask == 0x100) { goto next_byte; } |
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|
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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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|
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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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|
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bits->cur_mask <<= 1; |
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|
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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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|
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next_byte: |
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|
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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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|
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bits->cur_byte = *(*input)++; |
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bits->cur_mask = 1; |
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} |
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|
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done: |
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|
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IF_DEBUG2 (DP(RINT "(d) %u ", value)); |
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|
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(*valuep) = value; |
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return 0; |
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} |
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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 checks for |
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* non-zero bits. This is overly strict, but helps pass the single-bit-error regression |
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* 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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|
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return 0; |
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} |
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#endif |
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|
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static xd3_sec_stream* |
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xd3_get_secondary (xd3_stream *stream, xd3_sec_stream **sec_streamp) |
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{ |
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xd3_sec_stream *sec_stream; |
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|
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if ((sec_stream = *sec_streamp) == NULL) |
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{ |
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if ((*sec_streamp = stream->sec_type->alloc (stream)) == NULL) |
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{ |
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return NULL; |
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} |
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|
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sec_stream = *sec_streamp; |
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|
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/* If cuumulative stats, init once. */ |
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stream->sec_type->init (sec_stream); |
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} |
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|
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return sec_stream; |
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} |
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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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xd3_sec_stream *sec_stream; |
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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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|
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if ((sec_stream = xd3_get_secondary (stream, sec_streamp)) == NULL) { return ENOMEM; } |
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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, sect->buf_max, & dec_size)) || |
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(ret = xd3_decode_allocate (stream, dec_size, & sect->copied2, & sect->alloc2, NULL, NULL))) |
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{ |
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return ret; |
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} |
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|
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out_used = sect->copied2; |
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|
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if ((ret = stream->sec_type->decode (stream, sec_stream, |
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& sect->buf, sect->buf_max, |
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& out_used, out_used + dec_size))) { 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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|
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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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|
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sect->buf = sect->copied2; |
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sect->buf_max = sect->copied2 + dec_size; |
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|
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return 0; |
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} |
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|
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#if XD3_ENCODER |
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/* OPT: Should these be inline? */ |
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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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int bit) |
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{ |
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int ret; |
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|
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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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|
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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) { 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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|
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return 0; |
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} |
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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 : xd3_emit_byte (stream, output, bits->cur_byte); |
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} |
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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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|
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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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|
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do |
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{ |
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mask >>= 1; |
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|
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if ((ret = xd3_encode_bit (stream, output, bits, value & mask))) { return ret; } |
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} |
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while (mask != 1); |
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|
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IF_DEBUG2 (DP(RINT "(e) %u ", value)); |
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|
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return 0; |
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} |
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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_sec_stream *sec_stream; |
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xd3_output *tmp_head; |
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xd3_output *tmp_tail; |
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|
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usize_t comp_size; |
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usize_t orig_size; |
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|
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int ret; |
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|
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orig_size = xd3_sizeof_output (*head); |
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|
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if (orig_size < SECONDARY_MIN_INPUT) { return 0; } |
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|
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if ((sec_stream = xd3_get_secondary (stream, sec_streamp)) == NULL) { return ENOMEM; } |
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|
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tmp_head = xd3_alloc_output (stream, NULL); |
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|
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/* Encode the size, encode the data. @@ Encoding the size makes it simpler, but is a |
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* little gross. Should not need the entire section in contiguous memory, but it is |
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* 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_stream, *head, tmp_head, cfg))) { goto getout; } |
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|
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/* If the secondary compressor determines its no good, it returns XD3_NOSECOND. */ |
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|
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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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|
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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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|
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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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|
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if (comp_size < (orig_size - SECONDARY_MIN_SAVINGS)) |
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{ |
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IF_DEBUG1(DP(RINT "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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(double) comp_size / (double) orig_size)); |
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|
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xd3_free_output (stream, *head); |
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|
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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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|
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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_ */ |
