diff options
Diffstat (limited to 'fs/jffs2/compr_rubin.c')
| -rw-r--r-- | fs/jffs2/compr_rubin.c | 373 |
1 files changed, 373 insertions, 0 deletions
diff --git a/fs/jffs2/compr_rubin.c b/fs/jffs2/compr_rubin.c new file mode 100644 index 0000000..450d662 --- /dev/null +++ b/fs/jffs2/compr_rubin.c @@ -0,0 +1,373 @@ +/* + * JFFS2 -- Journalling Flash File System, Version 2. + * + * Copyright (C) 2001, 2002 Red Hat, Inc. + * + * Created by Arjan van de Ven <arjanv@redhat.com> + * + * For licensing information, see the file 'LICENCE' in this directory. + * + * $Id: compr_rubin.c,v 1.20 2004/06/23 16:34:40 havasi Exp $ + * + */ + + +#include <linux/string.h> +#include <linux/types.h> +#include <linux/jffs2.h> +#include "compr_rubin.h" +#include "histo_mips.h" +#include "compr.h" + +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=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, void *model) +{ + return rubin_do_compress(BIT_DIVIDER_MIPS, bits_mips, data_in, cpage_out, sourcelen, dstlen); +} +#endif +int jffs2_dynrubin_compress(unsigned char *data_in, unsigned char *cpage_out, + uint32_t *sourcelen, uint32_t *dstlen, void *model) +{ + 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); + } +} + + +int jffs2_rubinmips_decompress(unsigned char *data_in, unsigned char *cpage_out, + uint32_t sourcelen, uint32_t dstlen, void *model) +{ + rubin_do_decompress(BIT_DIVIDER_MIPS, bits_mips, data_in, cpage_out, sourcelen, dstlen); + return 0; +} + +int jffs2_dynrubin_decompress(unsigned char *data_in, unsigned char *cpage_out, + uint32_t sourcelen, uint32_t dstlen, void *model) +{ + 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); +} |
