cregit-Linux how code gets into the kernel

Release 4.12 lib/decompress_unlzma.c

Directory: lib
/* Lzma decompressor for Linux kernel. Shamelessly snarfed
 *from busybox 1.1.1
 *
 *Linux kernel adaptation
 *Copyright (C) 2006  Alain < alain@knaff.lu >
 *
 *Based on small lzma deflate implementation/Small range coder
 *implementation for lzma.
 *Copyright (C) 2006  Aurelien Jacobs < aurel@gnuage.org >
 *
 *Based on LzmaDecode.c from the LZMA SDK 4.22 (http://www.7-zip.org/)
 *Copyright (C) 1999-2005  Igor Pavlov
 *
 *Copyrights of the parts, see headers below.
 *
 *
 *This program is free software; you can redistribute it and/or
 *modify it under the terms of the GNU Lesser General Public
 *License as published by the Free Software Foundation; either
 *version 2.1 of the License, or (at your option) any later version.
 *
 *This program is distributed in the hope that it will be useful,
 *but WITHOUT ANY WARRANTY; without even the implied warranty of
 *MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *Lesser General Public License for more details.
 *
 *You should have received a copy of the GNU Lesser General Public
 *License along with this library; if not, write to the Free Software
 *Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#ifdef STATIC

#define PREBOOT
#else
#include <linux/decompress/unlzma.h>
#endif /* STATIC */

#include <linux/decompress/mm.h>


#define	MIN(a, b) (((a) < (b)) ? (a) : (b))


static long long INIT read_int(unsigned char *ptr, int size) { int i; long long ret = 0; for (i = 0; i < size; i++) ret = (ret << 8) | ptr[size-i-1]; return ret; }

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#define ENDIAN_CONVERT(x) \ x = (typeof(x))read_int((unsigned char *)&x, sizeof(x)) /* Small range coder implementation for lzma. *Copyright (C) 2006 Aurelien Jacobs < aurel@gnuage.org > * *Based on LzmaDecode.c from the LZMA SDK 4.22 (http://www.7-zip.org/) *Copyright (c) 1999-2005 Igor Pavlov */ #include <linux/compiler.h> #define LZMA_IOBUF_SIZE 0x10000 struct rc { long (*fill)(void*, unsigned long); uint8_t *ptr; uint8_t *buffer; uint8_t *buffer_end; long buffer_size; uint32_t code; uint32_t range; uint32_t bound; void (*error)(char *); }; #define RC_TOP_BITS 24 #define RC_MOVE_BITS 5 #define RC_MODEL_TOTAL_BITS 11
static long INIT nofill(void *buffer, unsigned long len) { return -1; }

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/* Called twice: once at startup and once in rc_normalize() */
static void INIT rc_read(struct rc *rc) { rc->buffer_size = rc->fill((char *)rc->buffer, LZMA_IOBUF_SIZE); if (rc->buffer_size <= 0) rc->error("unexpected EOF"); rc->ptr = rc->buffer; rc->buffer_end = rc->buffer + rc->buffer_size; }

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Alain Knaff6496.97%150.00%
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/* Called once */
static inline void INIT rc_init(struct rc *rc, long (*fill)(void*, unsigned long), char *buffer, long buffer_size) { if (fill) rc->fill = fill; else rc->fill = nofill; rc->buffer = (uint8_t *)buffer; rc->buffer_size = buffer_size; rc->buffer_end = rc->buffer + rc->buffer_size; rc->ptr = rc->buffer; rc->code = 0; rc->range = 0xFFFFFFFF; }

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Alain Knaff8485.71%133.33%
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static inline void INIT rc_init_code(struct rc *rc) { int i; for (i = 0; i < 5; i++) { if (rc->ptr >= rc->buffer_end) rc_read(rc); rc->code = (rc->code << 8) | *rc->ptr++; } }

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Alain Knaff64100.00%1100.00%
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/* Called twice, but one callsite is in inline'd rc_is_bit_0_helper() */
static void INIT rc_do_normalize(struct rc *rc) { if (rc->ptr >= rc->buffer_end) rc_read(rc); rc->range <<= 8; rc->code = (rc->code << 8) | *rc->ptr++; }

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static inline void INIT rc_normalize(struct rc *rc) { if (rc->range < (1 << RC_TOP_BITS)) rc_do_normalize(rc); }

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/* Called 9 times */ /* Why rc_is_bit_0_helper exists? *Because we want to always expose (rc->code < rc->bound) to optimizer */
static inline uint32_t INIT rc_is_bit_0_helper(struct rc *rc, uint16_t *p) { rc_normalize(rc); rc->bound = *p * (rc->range >> RC_MODEL_TOTAL_BITS); return rc->bound; }

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static inline int INIT rc_is_bit_0(struct rc *rc, uint16_t *p) { uint32_t t = rc_is_bit_0_helper(rc, p); return rc->code < t; }

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/* Called ~10 times, but very small, thus inlined */
static inline void INIT rc_update_bit_0(struct rc *rc, uint16_t *p) { rc->range = rc->bound; *p += ((1 << RC_MODEL_TOTAL_BITS) - *p) >> RC_MOVE_BITS; }

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static inline void INIT rc_update_bit_1(struct rc *rc, uint16_t *p) { rc->range -= rc->bound; rc->code -= rc->bound; *p -= *p >> RC_MOVE_BITS; }

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Alain Knaff4097.56%150.00%
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/* Called 4 times in unlzma loop */
static int INIT rc_get_bit(struct rc *rc, uint16_t *p, int *symbol) { if (rc_is_bit_0(rc, p)) { rc_update_bit_0(rc, p); *symbol *= 2; return 0; } else { rc_update_bit_1(rc, p); *symbol = *symbol * 2 + 1; return 1; } }

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/* Called once */
static inline int INIT rc_direct_bit(struct rc *rc) { rc_normalize(rc); rc->range >>= 1; if (rc->code >= rc->range) { rc->code -= rc->range; return 1; } return 0; }

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/* Called twice */
static inline void INIT rc_bit_tree_decode(struct rc *rc, uint16_t *p, int num_levels, int *symbol) { int i = num_levels; *symbol = 1; while (i--) rc_get_bit(rc, p + *symbol, symbol); *symbol -= 1 << num_levels; }

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Alain Knaff58100.00%1100.00%
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/* * Small lzma deflate implementation. * Copyright (C) 2006 Aurelien Jacobs < aurel@gnuage.org > * * Based on LzmaDecode.c from the LZMA SDK 4.22 (http://www.7-zip.org/) * Copyright (C) 1999-2005 Igor Pavlov */ struct lzma_header { uint8_t pos; uint32_t dict_size; uint64_t dst_size; } __attribute__ ((packed)) ; #define LZMA_BASE_SIZE 1846 #define LZMA_LIT_SIZE 768 #define LZMA_NUM_POS_BITS_MAX 4 #define LZMA_LEN_NUM_LOW_BITS 3 #define LZMA_LEN_NUM_MID_BITS 3 #define LZMA_LEN_NUM_HIGH_BITS 8 #define LZMA_LEN_CHOICE 0 #define LZMA_LEN_CHOICE_2 (LZMA_LEN_CHOICE + 1) #define LZMA_LEN_LOW (LZMA_LEN_CHOICE_2 + 1) #define LZMA_LEN_MID (LZMA_LEN_LOW \ + (1 << (LZMA_NUM_POS_BITS_MAX + LZMA_LEN_NUM_LOW_BITS))) #define LZMA_LEN_HIGH (LZMA_LEN_MID \ +(1 << (LZMA_NUM_POS_BITS_MAX + LZMA_LEN_NUM_MID_BITS))) #define LZMA_NUM_LEN_PROBS (LZMA_LEN_HIGH + (1 << LZMA_LEN_NUM_HIGH_BITS)) #define LZMA_NUM_STATES 12 #define LZMA_NUM_LIT_STATES 7 #define LZMA_START_POS_MODEL_INDEX 4 #define LZMA_END_POS_MODEL_INDEX 14 #define LZMA_NUM_FULL_DISTANCES (1 << (LZMA_END_POS_MODEL_INDEX >> 1)) #define LZMA_NUM_POS_SLOT_BITS 6 #define LZMA_NUM_LEN_TO_POS_STATES 4 #define LZMA_NUM_ALIGN_BITS 4 #define LZMA_MATCH_MIN_LEN 2 #define LZMA_IS_MATCH 0 #define LZMA_IS_REP (LZMA_IS_MATCH + (LZMA_NUM_STATES << LZMA_NUM_POS_BITS_MAX)) #define LZMA_IS_REP_G0 (LZMA_IS_REP + LZMA_NUM_STATES) #define LZMA_IS_REP_G1 (LZMA_IS_REP_G0 + LZMA_NUM_STATES) #define LZMA_IS_REP_G2 (LZMA_IS_REP_G1 + LZMA_NUM_STATES) #define LZMA_IS_REP_0_LONG (LZMA_IS_REP_G2 + LZMA_NUM_STATES) #define LZMA_POS_SLOT (LZMA_IS_REP_0_LONG \ + (LZMA_NUM_STATES << LZMA_NUM_POS_BITS_MAX)) #define LZMA_SPEC_POS (LZMA_POS_SLOT \ +(LZMA_NUM_LEN_TO_POS_STATES << LZMA_NUM_POS_SLOT_BITS)) #define LZMA_ALIGN (LZMA_SPEC_POS \ + LZMA_NUM_FULL_DISTANCES - LZMA_END_POS_MODEL_INDEX) #define LZMA_LEN_CODER (LZMA_ALIGN + (1 << LZMA_NUM_ALIGN_BITS)) #define LZMA_REP_LEN_CODER (LZMA_LEN_CODER + LZMA_NUM_LEN_PROBS) #define LZMA_LITERAL (LZMA_REP_LEN_CODER + LZMA_NUM_LEN_PROBS) struct writer { uint8_t *buffer; uint8_t previous_byte; size_t buffer_pos; int bufsize; size_t global_pos; long (*flush)(void*, unsigned long); struct lzma_header *header; }; struct cstate { int state; uint32_t rep0, rep1, rep2, rep3; };
static inline size_t INIT get_pos(struct writer *wr) { return wr->global_pos + wr->buffer_pos; }

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static inline uint8_t INIT peek_old_byte(struct writer *wr, uint32_t offs) { if (!wr->flush) { int32_t pos; while (offs > wr->header->dict_size) offs -= wr->header->dict_size; pos = wr->buffer_pos - offs; return wr->buffer[pos]; } else { uint32_t pos = wr->buffer_pos - offs; while (pos >= wr->header->dict_size) pos += wr->header->dict_size; return wr->buffer[pos]; } }

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static inline int INIT write_byte(struct writer *wr, uint8_t byte) { wr->buffer[wr->buffer_pos++] = wr->previous_byte = byte; if (wr->flush && wr->buffer_pos == wr->header->dict_size) { wr->buffer_pos = 0; wr->global_pos += wr->header->dict_size; if (wr->flush((char *)wr->buffer, wr->header->dict_size) != wr->header->dict_size) return -1; } return 0; }

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static inline int INIT copy_byte(struct writer *wr, uint32_t offs) { return write_byte(wr, peek_old_byte(wr, offs)); }

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static inline int INIT copy_bytes(struct writer *wr, uint32_t rep0, int len) { do { if (copy_byte(wr, rep0)) return -1; len--; } while (len != 0 && wr->buffer_pos < wr->header->dst_size); return len; }

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static inline int INIT process_bit0(struct writer *wr, struct rc *rc, struct cstate *cst, uint16_t *p, int pos_state, uint16_t *prob, int lc, uint32_t literal_pos_mask) { int mi = 1; rc_update_bit_0(rc, prob); prob = (p + LZMA_LITERAL + (LZMA_LIT_SIZE * (((get_pos(wr) & literal_pos_mask) << lc) + (wr->previous_byte >> (8 - lc)))) ); if (cst->state >= LZMA_NUM_LIT_STATES) { int match_byte = peek_old_byte(wr, cst->rep0); do { int bit; uint16_t *prob_lit; match_byte <<= 1; bit = match_byte & 0x100; prob_lit = prob + 0x100 + bit + mi; if (rc_get_bit(rc, prob_lit, &mi)) { if (!bit) break; } else { if (bit) break; } } while (mi < 0x100); } while (mi < 0x100) { uint16_t *prob_lit = prob + mi; rc_get_bit(rc, prob_lit, &mi); } if (cst->state < 4) cst->state = 0; else if (cst->state < 10) cst->state -= 3; else cst->state -= 6; return write_byte(wr, mi); }

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static inline int INIT process_bit1(struct writer *wr, struct rc *rc, struct cstate *cst, uint16_t *p, int pos_state, uint16_t *prob) { int offset; uint16_t *prob_len; int num_bits; int len; rc_update_bit_1(rc, prob); prob = p + LZMA_IS_REP + cst->state; if (rc_is_bit_0(rc, prob)) { rc_update_bit_0(rc, prob); cst->rep3 = cst->rep2; cst->rep2 = cst->rep1; cst->rep1 = cst->rep0; cst->state = cst->state < LZMA_NUM_LIT_STATES ? 0 : 3; prob = p + LZMA_LEN_CODER; } else { rc_update_bit_1(rc, prob); prob = p + LZMA_IS_REP_G0 + cst->state; if (rc_is_bit_0(rc, prob)) { rc_update_bit_0(rc, prob); prob = (p + LZMA_IS_REP_0_LONG + (cst->state << LZMA_NUM_POS_BITS_MAX) + pos_state); if (rc_is_bit_0(rc, prob)) { rc_update_bit_0(rc, prob); cst->state = cst->state < LZMA_NUM_LIT_STATES ? 9 : 11; return copy_byte(wr, cst->rep0); } else { rc_update_bit_1(rc, prob); } } else { uint32_t distance; rc_update_bit_1(rc, prob); prob = p + LZMA_IS_REP_G1 + cst->state; if (rc_is_bit_0(rc, prob)) { rc_update_bit_0(rc, prob); distance = cst->rep1; } else { rc_update_bit_1(rc, prob); prob = p + LZMA_IS_REP_G2 + cst->state; if (rc_is_bit_0(rc, prob)) { rc_update_bit_0(rc, prob); distance = cst->rep2; } else { rc_update_bit_1(rc, prob); distance = cst->rep3; cst->rep3 = cst->rep2; } cst->rep2 = cst->rep1; } cst->rep1 = cst->rep0; cst->rep0 = distance; } cst->state = cst->state < LZMA_NUM_LIT_STATES ? 8 : 11; prob = p + LZMA_REP_LEN_CODER; } prob_len = prob + LZMA_LEN_CHOICE; if (rc_is_bit_0(rc, prob_len)) { rc_update_bit_0(rc, prob_len); prob_len = (prob + LZMA_LEN_LOW + (pos_state << LZMA_LEN_NUM_LOW_BITS)); offset = 0; num_bits = LZMA_LEN_NUM_LOW_BITS; } else { rc_update_bit_1(rc, prob_len); prob_len = prob + LZMA_LEN_CHOICE_2; if (rc_is_bit_0(rc, prob_len)) { rc_update_bit_0(rc, prob_len); prob_len = (prob + LZMA_LEN_MID + (pos_state << LZMA_LEN_NUM_MID_BITS)); offset = 1 << LZMA_LEN_NUM_LOW_BITS; num_bits = LZMA_LEN_NUM_MID_BITS; } else { rc_update_bit_1(rc, prob_len); prob_len = prob + LZMA_LEN_HIGH; offset = ((1 << LZMA_LEN_NUM_LOW_BITS) + (1 << LZMA_LEN_NUM_MID_BITS)); num_bits = LZMA_LEN_NUM_HIGH_BITS; } } rc_bit_tree_decode(rc, prob_len, num_bits, &len); len += offset; if (cst->state < 4) { int pos_slot; cst->state += LZMA_NUM_LIT_STATES; prob = p + LZMA_POS_SLOT + ((len < LZMA_NUM_LEN_TO_POS_STATES ? len : LZMA_NUM_LEN_TO_POS_STATES - 1) << LZMA_NUM_POS_SLOT_BITS); rc_bit_tree_decode(rc, prob, LZMA_NUM_POS_SLOT_BITS, &pos_slot); if (pos_slot >= LZMA_START_POS_MODEL_INDEX) { int i, mi; num_bits = (pos_slot >> 1) - 1; cst->rep0 = 2 | (pos_slot & 1); if (pos_slot < LZMA_END_POS_MODEL_INDEX) { cst->rep0 <<= num_bits; prob = p + LZMA_SPEC_POS + cst->rep0 - pos_slot - 1; } else { num_bits -= LZMA_NUM_ALIGN_BITS; while (num_bits--) cst->rep0 = (cst->rep0 << 1) | rc_direct_bit(rc); prob = p + LZMA_ALIGN; cst->rep0 <<= LZMA_NUM_ALIGN_BITS; num_bits = LZMA_NUM_ALIGN_BITS; } i = 1; mi = 1; while (num_bits--) { if (rc_get_bit(rc, prob + mi, &mi)) cst->rep0 |= i; i <<= 1; } } else cst->rep0 = pos_slot; if (++(cst->rep0) == 0) return 0; if (cst->rep0 > wr->header->dict_size || cst->rep0 > get_pos(wr)) return -1; } len += LZMA_MATCH_MIN_LEN; return copy_bytes(wr, cst->rep0, len); }

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STATIC inline int INIT unlzma(unsigned char *buf, long in_len, long (*fill)(void*, unsigned long), long (*flush)(void*, unsigned long), unsigned char *output, long *posp, void(*error)(char *x) ) { struct lzma_header header; int lc, pb, lp; uint32_t pos_state_mask; uint32_t literal_pos_mask; uint16_t *p; int num_probs; struct rc rc; int i, mi; struct writer wr; struct cstate cst; unsigned char *inbuf; int ret = -1; rc.error = error; if (buf) inbuf = buf; else inbuf = malloc(LZMA_IOBUF_SIZE); if (!inbuf) { error("Could not allocate input buffer"); goto exit_0; } cst.state = 0; cst.rep0 = cst.rep1 = cst.rep2 = cst.rep3 = 1; wr.header = &header; wr.flush = flush; wr.global_pos = 0; wr.previous_byte = 0; wr.buffer_pos = 0; rc_init(&rc, fill, inbuf, in_len); for (i = 0; i < sizeof(header); i++) { if (rc.ptr >=