package com.wavpack.decoder;
/*
** WordsUtils.java
**
** Copyright (c) 2007 - 2008 Peter McQuillan
**
** All Rights Reserved.
**
** Distributed under the BSD Software License (see license.txt)
**
*/
class WordsUtils {
//////////////////////////////// local macros /////////////////////////////////
static int 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).
static int SLS = 8;
static int SLO = ((1 << (SLS - 1)));
// these control the time constant of the 3 median level breakpoints
static int DIV0 = 128; // 5/7 of samples
static int DIV1 = 64; // 10/49 of samples
static int DIV2 = 32; // 20/343 of samples
///////////////////////////// local table storage ////////////////////////////
static 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 int 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 int 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 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 ////////////////////////////////
// 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.
static int read_entropy_vars(WavpackStream wps, WavpackMetadata wpmd) {
byte byteptr[] = wpmd.data; //byteptr needs to be unsigned chars, so convert to int array
int[] b_array = new int[12];
int i = 0;
words_data w = new words_data();
for (i = 0; i < 6; i++) {
b_array[i] = (int) (byteptr[i] & 0xff);
}
w.holding_one = 0;
w.holding_zero = 0;
if (wpmd.byte_length != 12) {
if ((wps.wphdr.flags & (Defines.MONO_FLAG | Defines.FALSE_STEREO)) == 0) {
return Defines.FALSE;
}
}
w.c[0].median[0] = exp2s(b_array[0] + (b_array[1] << 8));
w.c[0].median[1] = exp2s(b_array[2] + (b_array[3] << 8));
w.c[0].median[2] = exp2s(b_array[4] + (b_array[5] << 8));
if ((wps.wphdr.flags & (Defines.MONO_FLAG | Defines.FALSE_STEREO)) == 0) {
for (i = 6; i < 12; i++) {
b_array[i] = (int) (byteptr[i] & 0xff);
}
w.c[1].median[0] = exp2s(b_array[6] + (b_array[7] << 8));
w.c[1].median[1] = exp2s(b_array[8] + (b_array[9] << 8));
w.c[1].median[2] = exp2s(b_array[10] + (b_array[11] << 8));
}
wps.w = w;
return Defines.TRUE;
}
// 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.
static int read_hybrid_profile(WavpackStream wps, WavpackMetadata wpmd) {
byte byteptr[] = wpmd.data;
int bytecnt = wpmd.byte_length;
int buffer_counter = 0;
int uns_buf = 0;
int uns_buf_plusone = 0;
if ((wps.wphdr.flags & Defines.HYBRID_BITRATE) != 0) {
uns_buf = (int) (byteptr[buffer_counter] & 0xff);
uns_buf_plusone = (int) (byteptr[buffer_counter + 1] & 0xff);
wps.w.c[0].slow_level = exp2s(uns_buf + (uns_buf_plusone << 8));
buffer_counter = buffer_counter + 2;
if ((wps.wphdr.flags & (Defines.MONO_FLAG | Defines.FALSE_STEREO)) == 0) {
uns_buf = (int) (byteptr[buffer_counter] & 0xff);
uns_buf_plusone = (int) (byteptr[buffer_counter + 1] & 0xff);
wps.w.c[1].slow_level = exp2s(uns_buf + (uns_buf_plusone << 8));
buffer_counter = buffer_counter + 2;
}
}
uns_buf = (int) (byteptr[buffer_counter] & 0xff);
uns_buf_plusone = (int) (byteptr[buffer_counter + 1] & 0xff);
wps.w.bitrate_acc[0] = (int) (uns_buf + (uns_buf_plusone << 8)) << 16;
buffer_counter = buffer_counter + 2;
if ((wps.wphdr.flags & (Defines.MONO_FLAG | Defines.FALSE_STEREO)) == 0) {
uns_buf = (int) (byteptr[buffer_counter] & 0xff);
uns_buf_plusone = (int) (byteptr[buffer_counter + 1] & 0xff);
wps.w.bitrate_acc[1] = (int) (uns_buf + (uns_buf_plusone << 8)) << 16;
buffer_counter = buffer_counter + 2;
}
if (buffer_counter < bytecnt) {
uns_buf = (int) (byteptr[buffer_counter] & 0xff);
uns_buf_plusone = (int) (byteptr[buffer_counter + 1] & 0xff);
wps.w.bitrate_delta[0] = exp2s((short) (uns_buf + (uns_buf_plusone << 8)));
buffer_counter = buffer_counter + 2;
if ((wps.wphdr.flags & (Defines.MONO_FLAG | Defines.FALSE_STEREO)) == 0) {
uns_buf = (int) (byteptr[buffer_counter] & 0xff);
uns_buf_plusone = (int) (byteptr[buffer_counter + 1] & 0xff);
wps.w.bitrate_delta[1] = exp2s((short) (uns_buf + (uns_buf_plusone << 8)));
buffer_counter = buffer_counter + 2;
}
if (buffer_counter < bytecnt)
return Defines.FALSE;
} else
wps.w.bitrate_delta[0] = wps.w.bitrate_delta[1] = 0;
return Defines.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.
static words_data update_error_limit(words_data w, long flags) {
int bitrate_0 = (int) ((w.bitrate_acc[0] += w.bitrate_delta[0]) >> 16);
if ((flags & (Defines.MONO_FLAG | Defines.FALSE_STEREO)) != 0) {
if ((flags & Defines.HYBRID_BITRATE) != 0) {
int slow_log_0 = (int) ((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 = (int) ((w.bitrate_acc[1] += w.bitrate_delta[1]) >> 16);
if ((flags & Defines.HYBRID_BITRATE) != 0) {
int slow_log_0 = (int) ((w.c[0].slow_level + SLO) >> SLS);
int slow_log_1 = (int) ((w.c[1].slow_level + SLO) >> SLS);
if ((flags & Defines.HYBRID_BALANCE) != 0) {
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);
}
}
return w;
}
// 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.
static int get_words(long nsamples, long flags, words_data w, Bitstream bs, int[] buffer) {
entropy_data[] c = w.c;
int csamples;
int buffer_counter = 0;
int entidx = 1;
if ((flags & (Defines.MONO_FLAG | Defines.FALSE_STEREO)) == 0) // if not mono
{
nsamples *= 2;
} else {
// it is mono
entidx = 0;
}
for (csamples = 0; csamples < nsamples; ++csamples) {
long ones_count, low, mid, high;
if ((flags & (Defines.MONO_FLAG | Defines.FALSE_STEREO)) == 0) // if not mono
{
if (entidx == 1)
entidx = 0;
else
entidx = 1;
}
if ((w.c[0].median[0] & ~1) == 0 && w.holding_zero == 0 && w.holding_one == 0
&& (w.c[1].median[0] & ~1) == 0) {
long mask;
int cbits;
if (w.zeros_acc > 0) {
--w.zeros_acc;
if (w.zeros_acc > 0) {
c[entidx].slow_level -= (c[entidx].slow_level + SLO) >> SLS;
buffer[buffer_counter] = 0;
buffer_counter++;
continue;
}
} else {
cbits = 0;
bs = BitsUtils.getbit(bs);
while (cbits < 33 && bs.bitval > 0) {
cbits++;
bs = BitsUtils.getbit(bs);
}
if (cbits == 33) {
break;
}
if (cbits < 2)
w.zeros_acc = cbits;
else {
--cbits;
for (mask = 1,
w.zeros_acc = 0; cbits > 0; mask <<= 1) {
bs = BitsUtils.getbit(bs);
if (bs.bitval > 0)
w.zeros_acc |= mask;
cbits--;
}
w.zeros_acc |= mask;
}
if (w.zeros_acc > 0) {
c[entidx].slow_level -= (c[entidx].slow_level + SLO) >> SLS;
w.c[0].median[0] = 0;
w.c[0].median[1] = 0;
w.c[0].median[2] = 0;
w.c[1].median[0] = 0;
w.c[1].median[1] = 0;
w.c[1].median[2] = 0;
buffer[buffer_counter] = 0;
buffer_counter++;
continue;
}
}
}
if (w.holding_zero > 0)
ones_count = w.holding_zero = 0;
else {
int next8;
int uns_buf;
if (bs.bc < 8) {
bs.ptr++;
bs.buf_index++;
if (bs.ptr == bs.end)
bs = BitsUtils.bs_read(bs);
uns_buf = bs.buf[bs.buf_index] & 0xff;
bs.sr = bs.sr | (uns_buf << bs.bc); // values in buffer must be unsigned
next8 = (int) (bs.sr & 0xff);
bs.bc += 8;
} else
next8 = (int) (bs.sr & 0xff);
if (next8 == 0xff) {
bs.bc -= 8;
bs.sr >>= 8;
ones_count = 8;
bs = BitsUtils.getbit(bs);
while (ones_count < (LIMIT_ONES + 1) && bs.bitval > 0) {
ones_count++;
bs = BitsUtils.getbit(bs);
}
if (ones_count == (LIMIT_ONES + 1)) {
break;
}
if (ones_count == LIMIT_ONES) {
long mask;
int cbits;
cbits = 0;
bs = BitsUtils.getbit(bs);
while (cbits < 33 && bs.bitval > 0) {
cbits++;
bs = BitsUtils.getbit(bs);
}
if (cbits == 33) {
break;
}
if (cbits < 2)
ones_count = cbits;
else {
for (mask = 1,
ones_count = 0; --cbits > 0; mask <<= 1) {
bs = BitsUtils.getbit(bs);
if (bs.bitval > 0)
ones_count |= mask;
}
ones_count |= mask;
}
ones_count += LIMIT_ONES;
}
} else {
bs.bc -= (ones_count = ones_count_table[next8]) + 1;
bs.sr = bs.sr >> ones_count + 1; // needs to be unsigned
}
if (w.holding_one > 0) {
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 = (int) (~w.holding_one & 1);
}
if ((flags & Defines.HYBRID_FLAG) > 0
&& ((flags & (Defines.MONO_FLAG | Defines.FALSE_STEREO)) > 0 || (csamples & 1) == 0))
w = update_error_limit(w, flags);
if (ones_count == 0) {
low = 0;
high = (((c[entidx].median[0]) >> 4) + 1) - 1;
c[entidx].median[0] -= (((c[entidx].median[0] + (DIV0 - 2)) / DIV0) * 2);
} else {
low = (((c[entidx].median[0]) >> 4) + 1);
c[entidx].median[0] += ((c[entidx].median[0] + DIV0) / DIV0) * 5;
if (ones_count == 1) {
high = low + (((c[entidx].median[1]) >> 4) + 1) - 1;
c[entidx].median[1] -= ((c[entidx].median[1] + (DIV1 - 2)) / DIV1) * 2;
} else {
low += (((c[entidx].median[1]) >> 4) + 1);
c[entidx].median[1] += ((c[entidx].median[1] + DIV1) / DIV1) * 5;
if (ones_count == 2) {
high = low + (((c[entidx].median[2]) >> 4) + 1) - 1;
c[entidx].median[2] -= ((c[entidx].median[2] + (DIV2 - 2)) / DIV2) * 2;
} else {
low += (ones_count - 2) * (((c[entidx].median[2]) >> 4) + 1);
high = low + (((c[entidx].median[2]) >> 4) + 1) - 1;
c[entidx].median[2] += ((c[entidx].median[2] + DIV2) / DIV2) * 5;
}
}
}
mid = (high + low + 1) >> 1;
if (c[entidx].error_limit == 0) {
mid = read_code(bs, high - low);
mid = mid + low;
} else
while (high - low > c[entidx].error_limit) {
bs = BitsUtils.getbit(bs);
if (bs.bitval > 0) {
mid = (high + (low = mid) + 1) >> 1;
} else {
mid = ((high = mid - 1) + low + 1) >> 1;
}
}
bs = BitsUtils.getbit(bs);
if (bs.bitval > 0) {
buffer[buffer_counter] = (int) ~mid;
} else {
buffer[buffer_counter] = (int) mid;
}
buffer_counter++;
if ((flags & Defines.HYBRID_BITRATE) > 0)
c[entidx].slow_level = c[entidx].slow_level - ((c[entidx].slow_level + SLO) >> SLS) + mylog2(mid);
}
w.c = c;
if ((flags & (Defines.MONO_FLAG | Defines.FALSE_STEREO)) != 0) {
return csamples;
} else {
return (csamples / 2);
}
}
static int count_bits(long av) {
if (av < (1 << 8)) {
return nbits_table[(int) av];
} else {
if (av < (1 << 16)) {
return nbits_table[(int) (av >>> 8)] + 8;
} else {
if (av < (1 << 24)) {
return nbits_table[(int) (av >>> 16)] + 16;
} else {
return nbits_table[(int) (av >>> 24)] + 24;
}
}
}
}
// 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 long read_code(Bitstream bs, long maxcode) {
int bitcount = count_bits(maxcode);
long extras = (1L << bitcount) - maxcode - 1, code;
if (bitcount == 0) {
return ((long) 0);
}
code = BitsUtils.getbits(bitcount - 1, bs);
code &= (1L << (bitcount - 1)) - 1;
if (code >= extras) {
code = (code << 1) - extras;
bs = BitsUtils.getbit(bs);
if (bs.bitval > 0)
++code;
}
return (code);
}
// 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(long avalue) {
int dbits;
if ((avalue += avalue >> 9) < (1 << 8)) {
dbits = nbits_table[(int) avalue];
return (dbits << 8) + log2_table[(int) (avalue << (9 - dbits)) & 0xff];
} else {
if (avalue < (1L << 16))
dbits = nbits_table[(int) (avalue >> 8)] + 8;
else if (avalue < (1L << 24))
dbits = nbits_table[(int) (avalue >> 16)] + 16;
else
dbits = nbits_table[(int) (avalue >> 24)] + 24;
return (dbits << 8) + log2_table[(int) (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(int value) {
if (value < 0) {
return -mylog2(-value);
} else {
return 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).
static int exp2s(int log) {
long value;
if (log < 0)
return -exp2s(-log);
value = exp2_table[log & 0xff] | 0x100;
if ((log >>= 8) <= 9)
return ((int) (value >> (9 - log)));
else
return ((int) (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.
static int restore_weight(byte weight) {
int result;
if ((result = (int) weight << 3) > 0)
result += (result + 64) >> 7;
return result;
}
}