//////////////////////////////////////////////////////////////////////////// // **** WAVPACK **** // // Hybrid Lossless Wavefile Compressor // // Copyright (c) 1998 - 2004 Conifer Software. // // All Rights Reserved. // //////////////////////////////////////////////////////////////////////////// // words.c // This module provides entropy word encoding and decoding functions using // a variation on the Rice method. This was introduced in version 3.93 // because it allows splitting the data into a "lossy" stream and a // "correction" stream in a very efficient manner and is therefore ideal // for the "hybrid" mode. For 4.0, the efficiency of this method was // significantly improved by moving away from the normal Rice restriction of // using powers of two for the modulus divisions and now the method can be // used for both hybrid and pure lossless encoding. // Samples are divided by median probabilities at 5/7 (71.43%), 10/49 (20.41%), // and 20/343 (5.83%). Each zone has 3.5 times fewer samples than the // previous. Using standard Rice coding on this data would result in 1.4 // bits per sample average (not counting sign bit). However, there is a // very simple encoding that is over 99% efficient with this data and // results in about 1.22 bits per sample. #include "wavpack.h" #include //////////////////////////////// local macros ///////////////////////////////// #define LIMIT_ONES 16 // maximum consecutive 1s sent for "div" data // these control the time constant "slow_level" which is used for hybrid mode // that controls bitrate as a function of residual level (HYBRID_BITRATE). #define SLS 8 #define SLO ((1 << (SLS - 1))) // these control the time constant of the 3 median level breakpoints #define DIV0 128 // 5/7 of samples #define DIV1 64 // 10/49 of samples #define DIV2 32 // 20/343 of samples // this macro retrieves the specified median breakpoint (without frac; min = 1) #define GET_MED(med) (((c->median [med]) >> 4) + 1) // These macros update the specified median breakpoints. Note that the median // is incremented when the sample is higher than the median, else decremented. // They are designed so that the median will never drop below 1 and the value // is essentially stationary if there are 2 increments for every 5 decrements. #define INC_MED0() (c->median [0] += ((c->median [0] + DIV0) / DIV0) * 5) #define DEC_MED0() (c->median [0] -= ((c->median [0] + (DIV0-2)) / DIV0) * 2) #define INC_MED1() (c->median [1] += ((c->median [1] + DIV1) / DIV1) * 5) #define DEC_MED1() (c->median [1] -= ((c->median [1] + (DIV1-2)) / DIV1) * 2) #define INC_MED2() (c->median [2] += ((c->median [2] + DIV2) / DIV2) * 5) #define DEC_MED2() (c->median [2] -= ((c->median [2] + (DIV2-2)) / DIV2) * 2) #define count_bits(av) ( \ (av) < (1 << 8) ? nbits_table [av] : \ ( \ (av) < (1L << 16) ? nbits_table [(av) >> 8] + 8 : \ ((av) < (1L << 24) ? nbits_table [(av) >> 16] + 16 : nbits_table [(av) >> 24] + 24) \ ) \ ) ///////////////////////////// local table storage //////////////////////////// const char nbits_table [] = { 0, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, // 0 - 15 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, // 16 - 31 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, // 32 - 47 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, // 48 - 63 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, // 64 - 79 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, // 80 - 95 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, // 96 - 111 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, // 112 - 127 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, // 128 - 143 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, // 144 - 159 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, // 160 - 175 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, // 176 - 191 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, // 192 - 207 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, // 208 - 223 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, // 224 - 239 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8 // 240 - 255 }; static const uchar log2_table [] = { 0x00, 0x01, 0x03, 0x04, 0x06, 0x07, 0x09, 0x0a, 0x0b, 0x0d, 0x0e, 0x10, 0x11, 0x12, 0x14, 0x15, 0x16, 0x18, 0x19, 0x1a, 0x1c, 0x1d, 0x1e, 0x20, 0x21, 0x22, 0x24, 0x25, 0x26, 0x28, 0x29, 0x2a, 0x2c, 0x2d, 0x2e, 0x2f, 0x31, 0x32, 0x33, 0x34, 0x36, 0x37, 0x38, 0x39, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, 0x41, 0x42, 0x43, 0x44, 0x45, 0x47, 0x48, 0x49, 0x4a, 0x4b, 0x4d, 0x4e, 0x4f, 0x50, 0x51, 0x52, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5a, 0x5c, 0x5d, 0x5e, 0x5f, 0x60, 0x61, 0x62, 0x63, 0x64, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, 0x70, 0x71, 0x72, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f, 0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0x9b, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f, 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7, 0xa8, 0xa9, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf, 0xb0, 0xb1, 0xb2, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf, 0xc0, 0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xcb, 0xcb, 0xcc, 0xcd, 0xce, 0xcf, 0xd0, 0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdc, 0xdd, 0xde, 0xdf, 0xe0, 0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe4, 0xe5, 0xe6, 0xe7, 0xe7, 0xe8, 0xe9, 0xea, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xee, 0xef, 0xf0, 0xf1, 0xf1, 0xf2, 0xf3, 0xf4, 0xf4, 0xf5, 0xf6, 0xf7, 0xf7, 0xf8, 0xf9, 0xf9, 0xfa, 0xfb, 0xfc, 0xfc, 0xfd, 0xfe, 0xff, 0xff }; static const uchar exp2_table [] = { 0x00, 0x01, 0x01, 0x02, 0x03, 0x03, 0x04, 0x05, 0x06, 0x06, 0x07, 0x08, 0x08, 0x09, 0x0a, 0x0b, 0x0b, 0x0c, 0x0d, 0x0e, 0x0e, 0x0f, 0x10, 0x10, 0x11, 0x12, 0x13, 0x13, 0x14, 0x15, 0x16, 0x16, 0x17, 0x18, 0x19, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1d, 0x1e, 0x1f, 0x20, 0x20, 0x21, 0x22, 0x23, 0x24, 0x24, 0x25, 0x26, 0x27, 0x28, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2c, 0x2d, 0x2e, 0x2f, 0x30, 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, 0x40, 0x41, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f, 0x50, 0x51, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5e, 0x5f, 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x87, 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f, 0x90, 0x91, 0x92, 0x93, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9f, 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xaf, 0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xbc, 0xbd, 0xbe, 0xbf, 0xc0, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc8, 0xc9, 0xca, 0xcb, 0xcd, 0xce, 0xcf, 0xd0, 0xd2, 0xd3, 0xd4, 0xd6, 0xd7, 0xd8, 0xd9, 0xdb, 0xdc, 0xdd, 0xde, 0xe0, 0xe1, 0xe2, 0xe4, 0xe5, 0xe6, 0xe8, 0xe9, 0xea, 0xec, 0xed, 0xee, 0xf0, 0xf1, 0xf2, 0xf4, 0xf5, 0xf6, 0xf8, 0xf9, 0xfa, 0xfc, 0xfd, 0xff }; static const char ones_count_table [] = { 0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,5, 0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,6, 0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,5, 0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,7, 0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,5, 0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,6, 0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,5, 0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,8 }; ///////////////////////////// executable code //////////////////////////////// void init_words (WavpackStream *wps) { CLEAR (wps->w); } static int mylog2 (unsigned long avalue); // Read the median log2 values from the specifed metadata structure, convert // them back to 32-bit unsigned values and store them. If length is not // exactly correct then we flag and return an error. int read_entropy_vars (WavpackStream *wps, WavpackMetadata *wpmd) { uchar *byteptr = wpmd->data; if (wpmd->byte_length != ((wps->wphdr.flags & MONO_FLAG) ? 6 : 12)) return FALSE; wps->w.c [0].median [0] = exp2s (byteptr [0] + (byteptr [1] << 8)); wps->w.c [0].median [1] = exp2s (byteptr [2] + (byteptr [3] << 8)); wps->w.c [0].median [2] = exp2s (byteptr [4] + (byteptr [5] << 8)); if (!(wps->wphdr.flags & MONO_FLAG)) { wps->w.c [1].median [0] = exp2s (byteptr [6] + (byteptr [7] << 8)); wps->w.c [1].median [1] = exp2s (byteptr [8] + (byteptr [9] << 8)); wps->w.c [1].median [2] = exp2s (byteptr [10] + (byteptr [11] << 8)); } return TRUE; } // Allocates the correct space in the metadata structure and writes the // current median values to it. Values are converted from 32-bit unsigned // to our internal 16-bit mylog2 values, and read_entropy_vars () is called // to read the values back because we must compensate for the loss through // the log function. void write_entropy_vars (WavpackStream *wps, WavpackMetadata *wpmd) { uchar *byteptr; int temp; byteptr = wpmd->data = wpmd->temp_data; wpmd->id = ID_ENTROPY_VARS; *byteptr++ = temp = mylog2 (wps->w.c [0].median [0]); *byteptr++ = temp >> 8; *byteptr++ = temp = mylog2 (wps->w.c [0].median [1]); *byteptr++ = temp >> 8; *byteptr++ = temp = mylog2 (wps->w.c [0].median [2]); *byteptr++ = temp >> 8; if (!(wps->wphdr.flags & MONO_FLAG)) { *byteptr++ = temp = mylog2 (wps->w.c [1].median [0]); *byteptr++ = temp >> 8; *byteptr++ = temp = mylog2 (wps->w.c [1].median [1]); *byteptr++ = temp >> 8; *byteptr++ = temp = mylog2 (wps->w.c [1].median [2]); *byteptr++ = temp >> 8; } wpmd->byte_length = byteptr - (uchar *) wpmd->data; read_entropy_vars (wps, wpmd); } // Read the hybrid related values from the specifed metadata structure, convert // them back to their internal formats and store them. The extended profile // stuff is not implemented yet, so return an error if we get more data than // we know what to do with. int read_hybrid_profile (WavpackStream *wps, WavpackMetadata *wpmd) { uchar *byteptr = wpmd->data; uchar *endptr = byteptr + wpmd->byte_length; if (wps->wphdr.flags & HYBRID_BITRATE) { wps->w.c [0].slow_level = exp2s (byteptr [0] + (byteptr [1] << 8)); byteptr += 2; if (!(wps->wphdr.flags & MONO_FLAG)) { wps->w.c [1].slow_level = exp2s (byteptr [0] + (byteptr [1] << 8)); byteptr += 2; } } wps->w.bitrate_acc [0] = (long)(byteptr [0] + (byteptr [1] << 8)) << 16; byteptr += 2; if (!(wps->wphdr.flags & MONO_FLAG)) { wps->w.bitrate_acc [1] = (long)(byteptr [0] + (byteptr [1] << 8)) << 16; byteptr += 2; } if (byteptr < endptr) { wps->w.bitrate_delta [0] = exp2s ((short)(byteptr [0] + (byteptr [1] << 8))); byteptr += 2; if (!(wps->wphdr.flags & MONO_FLAG)) { wps->w.bitrate_delta [1] = exp2s ((short)(byteptr [0] + (byteptr [1] << 8))); byteptr += 2; } if (byteptr < endptr) return FALSE; } else wps->w.bitrate_delta [0] = wps->w.bitrate_delta [1] = 0; return TRUE; } // This function is called during both encoding and decoding of hybrid data to // update the "error_limit" variable which determines the maximum sample error // allowed in the main bitstream. In the HYBRID_BITRATE mode (which is the only // currently implemented) this is calculated from the slow_level values and the // bitrate accumulators. Note that the bitrate accumulators can be changing. void update_error_limit (struct words_data *w, ulong flags) { int bitrate_0 = (w->bitrate_acc [0] += w->bitrate_delta [0]) >> 16; if (flags & MONO_FLAG) { if (flags & HYBRID_BITRATE) { int slow_log_0 = (w->c [0].slow_level + SLO) >> SLS; if (slow_log_0 - bitrate_0 > -0x100) w->c [0].error_limit = exp2s (slow_log_0 - bitrate_0 + 0x100); else w->c [0].error_limit = 0; } else w->c [0].error_limit = exp2s (bitrate_0); } else { int bitrate_1 = (w->bitrate_acc [1] += w->bitrate_delta [1]) >> 16; if (flags & HYBRID_BITRATE) { int slow_log_0 = (w->c [0].slow_level + SLO) >> SLS; int slow_log_1 = (w->c [1].slow_level + SLO) >> SLS; if (flags & HYBRID_BALANCE) { int balance = (slow_log_1 - slow_log_0 + bitrate_1 + 1) >> 1; if (balance > bitrate_0) { bitrate_1 = bitrate_0 * 2; bitrate_0 = 0; } else if (-balance > bitrate_0) { bitrate_0 = bitrate_0 * 2; bitrate_1 = 0; } else { bitrate_1 = bitrate_0 + balance; bitrate_0 = bitrate_0 - balance; } } if (slow_log_0 - bitrate_0 > -0x100) w->c [0].error_limit = exp2s (slow_log_0 - bitrate_0 + 0x100); else w->c [0].error_limit = 0; if (slow_log_1 - bitrate_1 > -0x100) w->c [1].error_limit = exp2s (slow_log_1 - bitrate_1 + 0x100); else w->c [1].error_limit = 0; } else { w->c [0].error_limit = exp2s (bitrate_0); w->c [1].error_limit = exp2s (bitrate_1); } } } static ulong read_code (Bitstream *bs, ulong maxcode); // Read the next word from the bitstream "wvbits" and return the value. This // function can be used for hybrid or lossless streams, but since an // optimized version is available for lossless this function would normally // be used for hybrid only. If a hybrid lossless stream is being read then // the "correction" offset is written at the specified pointer. A return value // of WORD_EOF indicates that the end of the bitstream was reached (all 1s) or // some other error occurred. long get_words (long *buffer, int nsamples, ulong flags, struct words_data *w, Bitstream *bs) { register struct entropy_data *c = w->c; int csamples; if (!(flags & MONO_FLAG)) nsamples *= 2; for (csamples = 0; csamples < nsamples; ++csamples) { ulong ones_count, low, mid, high; if (!(flags & MONO_FLAG)) c = w->c + (csamples & 1); if (!(w->c [0].median [0] & ~1) && !w->holding_zero && !w->holding_one && !(w->c [1].median [0] & ~1)) { ulong mask; int cbits; if (w->zeros_acc) { if (--w->zeros_acc) { c->slow_level -= (c->slow_level + SLO) >> SLS; *buffer++ = 0; continue; } } else { for (cbits = 0; cbits < 33 && getbit (bs); ++cbits); if (cbits == 33) break; if (cbits < 2) w->zeros_acc = cbits; else { for (mask = 1, w->zeros_acc = 0; --cbits; mask <<= 1) if (getbit (bs)) w->zeros_acc |= mask; w->zeros_acc |= mask; } if (w->zeros_acc) { c->slow_level -= (c->slow_level + SLO) >> SLS; CLEAR (w->c [0].median); CLEAR (w->c [1].median); *buffer++ = 0; continue; } } } if (w->holding_zero) ones_count = w->holding_zero = 0; else { int next8; if (bs->bc < 8) { if (++(bs->ptr) == bs->end) bs->wrap (bs); next8 = (bs->sr |= *(bs->ptr) << bs->bc) & 0xff; bs->bc += 8; } else next8 = bs->sr & 0xff; if (next8 == 0xff) { bs->bc -= 8; bs->sr >>= 8; for (ones_count = 8; ones_count < (LIMIT_ONES + 1) && getbit (bs); ++ones_count); if (ones_count == (LIMIT_ONES + 1)) break; if (ones_count == LIMIT_ONES) { ulong mask; int cbits; for (cbits = 0; cbits < 33 && getbit (bs); ++cbits); if (cbits == 33) break; if (cbits < 2) ones_count = cbits; else { for (mask = 1, ones_count = 0; --cbits; mask <<= 1) if (getbit (bs)) ones_count |= mask; ones_count |= mask; } ones_count += LIMIT_ONES; } } else { bs->bc -= (ones_count = ones_count_table [next8]) + 1; bs->sr >>= ones_count + 1; } if (w->holding_one) { w->holding_one = ones_count & 1; ones_count = (ones_count >> 1) + 1; } else { w->holding_one = ones_count & 1; ones_count >>= 1; } w->holding_zero = ~w->holding_one & 1; } if ((flags & HYBRID_FLAG) && ((flags & MONO_FLAG) || !(csamples & 1))) update_error_limit (w, flags); if (ones_count == 0) { low = 0; high = GET_MED (0) - 1; DEC_MED0 (); } else { low = GET_MED (0); INC_MED0 (); if (ones_count == 1) { high = low + GET_MED (1) - 1; DEC_MED1 (); } else { low += GET_MED (1); INC_MED1 (); if (ones_count == 2) { high = low + GET_MED (2) - 1; DEC_MED2 (); } else { low += (ones_count - 2) * GET_MED (2); high = low + GET_MED (2) - 1; INC_MED2 (); } } } mid = (high + low + 1) >> 1; if (!c->error_limit) mid = read_code (bs, high - low) + low; else while (high - low > c->error_limit) { if (getbit (bs)) mid = (high + (low = mid) + 1) >> 1; else mid = ((high = mid - 1) + low + 1) >> 1; } *buffer++ = getbit (bs) ? ~mid : mid; if (flags & HYBRID_BITRATE) c->slow_level = c->slow_level - ((c->slow_level + SLO) >> SLS) + mylog2 (mid); } return (flags & MONO_FLAG) ? csamples : (csamples / 2); } // Read a single unsigned value from the specified bitstream with a value // from 0 to maxcode. If there are exactly a power of two number of possible // codes then this will read a fixed number of bits; otherwise it reads the // minimum number of bits and then determines whether another bit is needed // to define the code. static ulong read_code (Bitstream *bs, ulong maxcode) { int bitcount = count_bits (maxcode); ulong extras = (1L << bitcount) - maxcode - 1, code; if (!bitcount) return 0; getbits (&code, bitcount - 1, bs); code &= (1L << (bitcount - 1)) - 1; if (code >= extras) { code = (code << 1) - extras; if (getbit (bs)) ++code; } return code; } void send_words (long *buffer, int nsamples, ulong flags, struct words_data *w, Bitstream *bs) { register struct entropy_data *c = w->c; if (!(flags & MONO_FLAG)) nsamples *= 2; while (nsamples--) { long value = *buffer++; int sign = (value < 0) ? 1 : 0; ulong ones_count, low, high; if (!(flags & MONO_FLAG)) c = w->c + (~nsamples & 1); if (!(w->c [0].median [0] & ~1) && !w->holding_zero && !(w->c [1].median [0] & ~1)) { if (w->zeros_acc) { if (value) flush_word (w, bs); else { w->zeros_acc++; continue; } } else if (value) { putbit_0 (bs); } else { CLEAR (w->c [0].median); CLEAR (w->c [1].median); w->zeros_acc = 1; continue; } } if (sign) value = ~value; if ((unsigned long) value < GET_MED (0)) { ones_count = low = 0; high = GET_MED (0) - 1; DEC_MED0 (); } else { low = GET_MED (0); INC_MED0 (); if (value - low < GET_MED (1)) { ones_count = 1; high = low + GET_MED (1) - 1; DEC_MED1 (); } else { low += GET_MED (1); INC_MED1 (); if (value - low < GET_MED (2)) { ones_count = 2; high = low + GET_MED (2) - 1; DEC_MED2 (); } else { ones_count = 2 + (value - low) / GET_MED (2); low += (ones_count - 2) * GET_MED (2); high = low + GET_MED (2) - 1; INC_MED2 (); } } } if (w->holding_zero) { if (ones_count) w->holding_one++; flush_word (w, bs); if (ones_count) { w->holding_zero = 1; ones_count--; } else w->holding_zero = 0; } else w->holding_zero = 1; w->holding_one = ones_count * 2; if (high != low) { ulong maxcode = high - low, code = value - low; int bitcount = count_bits (maxcode); ulong extras = (1L << bitcount) - maxcode - 1; if (code < extras) { w->pend_data |= code << w->pend_count; w->pend_count += bitcount - 1; } else { w->pend_data |= ((code + extras) >> 1) << w->pend_count; w->pend_count += bitcount - 1; w->pend_data |= ((code + extras) & 1) << w->pend_count++; } } w->pend_data |= ((long) sign << w->pend_count++); if (!w->holding_zero) flush_word (w, bs); } } // Used by send_word() and send_word_lossless() to actually send most the // accumulated data onto the bitstream. This is also called directly from // clients when all words have been sent. void flush_word (struct words_data *w, Bitstream *bs) { int cbits; if (w->zeros_acc) { cbits = count_bits (w->zeros_acc); while (cbits--) { putbit_1 (bs); } putbit_0 (bs); while (w->zeros_acc > 1) { putbit (w->zeros_acc & 1, bs); w->zeros_acc >>= 1; } w->zeros_acc = 0; } if (w->holding_one) { if (w->holding_one >= LIMIT_ONES) { putbits ((1L << LIMIT_ONES) - 1, LIMIT_ONES + 1, bs); w->holding_one -= LIMIT_ONES; cbits = count_bits (w->holding_one); while (cbits--) { putbit_1 (bs); } putbit_0 (bs); while (w->holding_one > 1) { putbit (w->holding_one & 1, bs); w->holding_one >>= 1; } w->holding_zero = 0; } else putbits ((1L << w->holding_one) - 1, w->holding_one, bs); w->holding_one = 0; } if (w->holding_zero) { putbit_0 (bs); w->holding_zero = 0; } if (w->pend_count) { while (w->pend_count > 24) { putbit (w->pend_data & 1, bs); w->pend_data >>= 1; w->pend_count--; } putbits (w->pend_data, w->pend_count, bs); w->pend_data = w->pend_count = 0; } } // The concept of a base 2 logarithm is used in many parts of WavPack. It is // a way of sufficiently accurately representing 32-bit signed and unsigned // values storing only 16 bits (actually fewer). It is also used in the hybrid // mode for quickly comparing the relative magnitude of large values (i.e. // division) and providing smooth exponentials using only addition. // These are not strict logarithms in that they become linear around zero and // can therefore represent both zero and negative values. They have 8 bits // of precision and in "roundtrip" conversions the total error never exceeds 1 // part in 225 except for the cases of +/-115 and +/-195 (which error by 1). // This function returns the log2 for the specified 32-bit unsigned value. // The maximum value allowed is about 0xff800000 and returns 8447. static int mylog2 (unsigned long avalue) { int dbits; if ((avalue += avalue >> 9) < (1 << 8)) { dbits = nbits_table [avalue]; return (dbits << 8) + log2_table [(avalue << (9 - dbits)) & 0xff]; } else { if (avalue < (1L << 16)) dbits = nbits_table [avalue >> 8] + 8; else if (avalue < (1L << 24)) dbits = nbits_table [avalue >> 16] + 16; else dbits = nbits_table [avalue >> 24] + 24; return (dbits << 8) + log2_table [(avalue >> (dbits - 9)) & 0xff]; } } // This function returns the log2 for the specified 32-bit signed value. // All input values are valid and the return values are in the range of // +/- 8192. int log2s (long value) { return (value < 0) ? -mylog2 (-value) : mylog2 (value); } // This function returns the original integer represented by the supplied // logarithm (at least within the provided accuracy). The log is signed, // but since a full 32-bit value is returned this can be used for unsigned // conversions as well (i.e. the input range is -8192 to +8447). long exp2s (int log) { ulong value; if (log < 0) return -exp2s (-log); value = exp2_table [log & 0xff] | 0x100; if ((log >>= 8) <= 9) return value >> (9 - log); else return value << (log - 9); } // These two functions convert internal weights (which are normally +/-1024) // to and from an 8-bit signed character version for storage in metadata. The // weights are clipped here in the case that they are outside that range. signed char store_weight (int weight) { if (weight > 1024) weight = 1024; else if (weight < -1024) weight = -1024; if (weight > 0) weight -= (weight + 64) >> 7; return (weight + 4) >> 3; } int restore_weight (signed char weight) { int result; if ((result = (int) weight << 3) > 0) result += (result + 64) >> 7; return result; }