| /* |
| * JFFS2 -- Journalling Flash File System, Version 2. |
| * |
| * Copyright © 2001-2007 Red Hat, Inc. |
| * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org> |
| * |
| * Created by Arjan van de Ven <arjanv@redhat.com> |
| * |
| * For licensing information, see the file 'LICENCE' in this directory. |
| * |
| */ |
| |
| #include <linux/string.h> |
| #include <linux/types.h> |
| #include <linux/jffs2.h> |
| #include <linux/errno.h> |
| #include "compr.h" |
| |
| |
| #define RUBIN_REG_SIZE 16 |
| #define UPPER_BIT_RUBIN (((long) 1)<<(RUBIN_REG_SIZE-1)) |
| #define LOWER_BITS_RUBIN ((((long) 1)<<(RUBIN_REG_SIZE-1))-1) |
| |
| |
| #define BIT_DIVIDER_MIPS 1043 |
| static int bits_mips[8] = { 277, 249, 290, 267, 229, 341, 212, 241}; |
| |
| struct pushpull { |
| unsigned char *buf; |
| unsigned int buflen; |
| unsigned int ofs; |
| unsigned int reserve; |
| }; |
| |
| struct rubin_state { |
| unsigned long p; |
| unsigned long q; |
| unsigned long rec_q; |
| long bit_number; |
| struct pushpull pp; |
| int bit_divider; |
| int bits[8]; |
| }; |
| |
| static inline void init_pushpull(struct pushpull *pp, char *buf, |
| unsigned buflen, unsigned ofs, |
| unsigned reserve) |
| { |
| pp->buf = buf; |
| pp->buflen = buflen; |
| pp->ofs = ofs; |
| pp->reserve = reserve; |
| } |
| |
| static inline int pushbit(struct pushpull *pp, int bit, int use_reserved) |
| { |
| if (pp->ofs >= pp->buflen - (use_reserved?0:pp->reserve)) |
| return -ENOSPC; |
| |
| if (bit) |
| pp->buf[pp->ofs >> 3] |= (1<<(7-(pp->ofs & 7))); |
| else |
| pp->buf[pp->ofs >> 3] &= ~(1<<(7-(pp->ofs & 7))); |
| |
| pp->ofs++; |
| |
| return 0; |
| } |
| |
| static inline int pushedbits(struct pushpull *pp) |
| { |
| return pp->ofs; |
| } |
| |
| static inline int pullbit(struct pushpull *pp) |
| { |
| int bit; |
| |
| bit = (pp->buf[pp->ofs >> 3] >> (7-(pp->ofs & 7))) & 1; |
| |
| pp->ofs++; |
| return bit; |
| } |
| |
| static inline int pulledbits(struct pushpull *pp) |
| { |
| return pp->ofs; |
| } |
| |
| |
| static void init_rubin(struct rubin_state *rs, int div, int *bits) |
| { |
| int c; |
| |
| rs->q = 0; |
| rs->p = (long) (2 * UPPER_BIT_RUBIN); |
| rs->bit_number = (long) 0; |
| rs->bit_divider = div; |
| |
| for (c=0; c<8; c++) |
| rs->bits[c] = bits[c]; |
| } |
| |
| |
| static int encode(struct rubin_state *rs, long A, long B, int symbol) |
| { |
| |
| long i0, i1; |
| int ret; |
| |
| while ((rs->q >= UPPER_BIT_RUBIN) || |
| ((rs->p + rs->q) <= UPPER_BIT_RUBIN)) { |
| rs->bit_number++; |
| |
| ret = pushbit(&rs->pp, (rs->q & UPPER_BIT_RUBIN) ? 1 : 0, 0); |
| if (ret) |
| return ret; |
| rs->q &= LOWER_BITS_RUBIN; |
| rs->q <<= 1; |
| rs->p <<= 1; |
| } |
| i0 = A * rs->p / (A + B); |
| if (i0 <= 0) |
| i0 = 1; |
| |
| if (i0 >= rs->p) |
| i0 = rs->p - 1; |
| |
| i1 = rs->p - i0; |
| |
| if (symbol == 0) |
| rs->p = i0; |
| else { |
| rs->p = i1; |
| rs->q += i0; |
| } |
| return 0; |
| } |
| |
| |
| static void end_rubin(struct rubin_state *rs) |
| { |
| |
| int i; |
| |
| for (i = 0; i < RUBIN_REG_SIZE; i++) { |
| pushbit(&rs->pp, (UPPER_BIT_RUBIN & rs->q) ? 1 : 0, 1); |
| rs->q &= LOWER_BITS_RUBIN; |
| rs->q <<= 1; |
| } |
| } |
| |
| |
| static void init_decode(struct rubin_state *rs, int div, int *bits) |
| { |
| init_rubin(rs, div, bits); |
| |
| /* behalve lower */ |
| rs->rec_q = 0; |
| |
| for (rs->bit_number = 0; rs->bit_number++ < RUBIN_REG_SIZE; |
| rs->rec_q = rs->rec_q * 2 + (long) (pullbit(&rs->pp))) |
| ; |
| } |
| |
| static void __do_decode(struct rubin_state *rs, unsigned long p, |
| unsigned long q) |
| { |
| register unsigned long lower_bits_rubin = LOWER_BITS_RUBIN; |
| unsigned long rec_q; |
| int c, bits = 0; |
| |
| /* |
| * First, work out how many bits we need from the input stream. |
| * Note that we have already done the initial check on this |
| * loop prior to calling this function. |
| */ |
| do { |
| bits++; |
| q &= lower_bits_rubin; |
| q <<= 1; |
| p <<= 1; |
| } while ((q >= UPPER_BIT_RUBIN) || ((p + q) <= UPPER_BIT_RUBIN)); |
| |
| rs->p = p; |
| rs->q = q; |
| |
| rs->bit_number += bits; |
| |
| /* |
| * Now get the bits. We really want this to be "get n bits". |
| */ |
| rec_q = rs->rec_q; |
| do { |
| c = pullbit(&rs->pp); |
| rec_q &= lower_bits_rubin; |
| rec_q <<= 1; |
| rec_q += c; |
| } while (--bits); |
| rs->rec_q = rec_q; |
| } |
| |
| static int decode(struct rubin_state *rs, long A, long B) |
| { |
| unsigned long p = rs->p, q = rs->q; |
| long i0, threshold; |
| int symbol; |
| |
| if (q >= UPPER_BIT_RUBIN || ((p + q) <= UPPER_BIT_RUBIN)) |
| __do_decode(rs, p, q); |
| |
| i0 = A * rs->p / (A + B); |
| if (i0 <= 0) |
| i0 = 1; |
| |
| if (i0 >= rs->p) |
| i0 = rs->p - 1; |
| |
| threshold = rs->q + i0; |
| symbol = rs->rec_q >= threshold; |
| if (rs->rec_q >= threshold) { |
| rs->q += i0; |
| i0 = rs->p - i0; |
| } |
| |
| rs->p = i0; |
| |
| return symbol; |
| } |
| |
| |
| |
| static int out_byte(struct rubin_state *rs, unsigned char byte) |
| { |
| int i, ret; |
| struct rubin_state rs_copy; |
| rs_copy = *rs; |
| |
| for (i=0; i<8; i++) { |
| ret = encode(rs, rs->bit_divider-rs->bits[i], |
| rs->bits[i], byte & 1); |
| if (ret) { |
| /* Failed. Restore old state */ |
| *rs = rs_copy; |
| return ret; |
| } |
| byte >>= 1 ; |
| } |
| return 0; |
| } |
| |
| static int in_byte(struct rubin_state *rs) |
| { |
| int i, result = 0, bit_divider = rs->bit_divider; |
| |
| for (i = 0; i < 8; i++) |
| result |= decode(rs, bit_divider - rs->bits[i], |
| rs->bits[i]) << i; |
| |
| return result; |
| } |
| |
| |
| |
| static int rubin_do_compress(int bit_divider, int *bits, unsigned char *data_in, |
| unsigned char *cpage_out, uint32_t *sourcelen, |
| uint32_t *dstlen) |
| { |
| int outpos = 0; |
| int pos=0; |
| struct rubin_state rs; |
| |
| init_pushpull(&rs.pp, cpage_out, *dstlen * 8, 0, 32); |
| |
| init_rubin(&rs, bit_divider, bits); |
| |
| while (pos < (*sourcelen) && !out_byte(&rs, data_in[pos])) |
| pos++; |
| |
| end_rubin(&rs); |
| |
| if (outpos > pos) { |
| /* We failed */ |
| return -1; |
| } |
| |
| /* Tell the caller how much we managed to compress, |
| * and how much space it took */ |
| |
| outpos = (pushedbits(&rs.pp)+7)/8; |
| |
| if (outpos >= pos) |
| return -1; /* We didn't actually compress */ |
| *sourcelen = pos; |
| *dstlen = outpos; |
| return 0; |
| } |
| #if 0 |
| /* _compress returns the compressed size, -1 if bigger */ |
| int jffs2_rubinmips_compress(unsigned char *data_in, unsigned char *cpage_out, |
| uint32_t *sourcelen, uint32_t *dstlen) |
| { |
| return rubin_do_compress(BIT_DIVIDER_MIPS, bits_mips, data_in, |
| cpage_out, sourcelen, dstlen); |
| } |
| #endif |
| static int jffs2_dynrubin_compress(unsigned char *data_in, |
| unsigned char *cpage_out, |
| uint32_t *sourcelen, uint32_t *dstlen) |
| { |
| int bits[8]; |
| unsigned char histo[256]; |
| int i; |
| int ret; |
| uint32_t mysrclen, mydstlen; |
| |
| mysrclen = *sourcelen; |
| mydstlen = *dstlen - 8; |
| |
| if (*dstlen <= 12) |
| return -1; |
| |
| memset(histo, 0, 256); |
| for (i=0; i<mysrclen; i++) |
| histo[data_in[i]]++; |
| memset(bits, 0, sizeof(int)*8); |
| for (i=0; i<256; i++) { |
| if (i&128) |
| bits[7] += histo[i]; |
| if (i&64) |
| bits[6] += histo[i]; |
| if (i&32) |
| bits[5] += histo[i]; |
| if (i&16) |
| bits[4] += histo[i]; |
| if (i&8) |
| bits[3] += histo[i]; |
| if (i&4) |
| bits[2] += histo[i]; |
| if (i&2) |
| bits[1] += histo[i]; |
| if (i&1) |
| bits[0] += histo[i]; |
| } |
| |
| for (i=0; i<8; i++) { |
| bits[i] = (bits[i] * 256) / mysrclen; |
| if (!bits[i]) bits[i] = 1; |
| if (bits[i] > 255) bits[i] = 255; |
| cpage_out[i] = bits[i]; |
| } |
| |
| ret = rubin_do_compress(256, bits, data_in, cpage_out+8, &mysrclen, |
| &mydstlen); |
| if (ret) |
| return ret; |
| |
| /* Add back the 8 bytes we took for the probabilities */ |
| mydstlen += 8; |
| |
| if (mysrclen <= mydstlen) { |
| /* We compressed */ |
| return -1; |
| } |
| |
| *sourcelen = mysrclen; |
| *dstlen = mydstlen; |
| return 0; |
| } |
| |
| static void rubin_do_decompress(int bit_divider, int *bits, |
| unsigned char *cdata_in, |
| unsigned char *page_out, uint32_t srclen, |
| uint32_t destlen) |
| { |
| int outpos = 0; |
| struct rubin_state rs; |
| |
| init_pushpull(&rs.pp, cdata_in, srclen, 0, 0); |
| init_decode(&rs, bit_divider, bits); |
| |
| while (outpos < destlen) |
| page_out[outpos++] = in_byte(&rs); |
| } |
| |
| |
| static int jffs2_rubinmips_decompress(unsigned char *data_in, |
| unsigned char *cpage_out, |
| uint32_t sourcelen, uint32_t dstlen) |
| { |
| rubin_do_decompress(BIT_DIVIDER_MIPS, bits_mips, data_in, |
| cpage_out, sourcelen, dstlen); |
| return 0; |
| } |
| |
| static int jffs2_dynrubin_decompress(unsigned char *data_in, |
| unsigned char *cpage_out, |
| uint32_t sourcelen, uint32_t dstlen) |
| { |
| int bits[8]; |
| int c; |
| |
| for (c=0; c<8; c++) |
| bits[c] = data_in[c]; |
| |
| rubin_do_decompress(256, bits, data_in+8, cpage_out, sourcelen-8, |
| dstlen); |
| return 0; |
| } |
| |
| static struct jffs2_compressor jffs2_rubinmips_comp = { |
| .priority = JFFS2_RUBINMIPS_PRIORITY, |
| .name = "rubinmips", |
| .compr = JFFS2_COMPR_DYNRUBIN, |
| .compress = NULL, /*&jffs2_rubinmips_compress,*/ |
| .decompress = &jffs2_rubinmips_decompress, |
| #ifdef JFFS2_RUBINMIPS_DISABLED |
| .disabled = 1, |
| #else |
| .disabled = 0, |
| #endif |
| }; |
| |
| int jffs2_rubinmips_init(void) |
| { |
| return jffs2_register_compressor(&jffs2_rubinmips_comp); |
| } |
| |
| void jffs2_rubinmips_exit(void) |
| { |
| jffs2_unregister_compressor(&jffs2_rubinmips_comp); |
| } |
| |
| static struct jffs2_compressor jffs2_dynrubin_comp = { |
| .priority = JFFS2_DYNRUBIN_PRIORITY, |
| .name = "dynrubin", |
| .compr = JFFS2_COMPR_RUBINMIPS, |
| .compress = jffs2_dynrubin_compress, |
| .decompress = &jffs2_dynrubin_decompress, |
| #ifdef JFFS2_DYNRUBIN_DISABLED |
| .disabled = 1, |
| #else |
| .disabled = 0, |
| #endif |
| }; |
| |
| int jffs2_dynrubin_init(void) |
| { |
| return jffs2_register_compressor(&jffs2_dynrubin_comp); |
| } |
| |
| void jffs2_dynrubin_exit(void) |
| { |
| jffs2_unregister_compressor(&jffs2_dynrubin_comp); |
| } |