360 lines
7.7 KiB
C
360 lines
7.7 KiB
C
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#include "layer3.h"
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#include "l3huff.h"
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//#ifdef _MSC_VER
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//#pragma warning(disable: 4505)
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//#endif
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/*===============================================================*/
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/* max bits required for any lookup - change if htable changes */
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/* quad required 10 bit w/signs must have (MAXBITS+2) >= 10 */
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#define MAXBITS 9
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static HUFF_ELEMENT huff_table_0[] =
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{0, 0, 0, 64}; /* dummy must not use */
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/*-- 6 bit lookup (purgebits, value) --*/
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static unsigned char quad_table_a[][2] =
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{
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6, 11, 6, 15, 6, 13, 6, 14, 6, 7, 6, 5, 5, 9,
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5, 9, 5, 6, 5, 6, 5, 3, 5, 3, 5, 10, 5, 10,
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5, 12, 5, 12, 4, 2, 4, 2, 4, 2, 4, 2, 4, 1,
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4, 1, 4, 1, 4, 1, 4, 4, 4, 4, 4, 4, 4, 4,
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4, 8, 4, 8, 4, 8, 4, 8, 1, 0, 1, 0, 1, 0,
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1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0,
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1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0,
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1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0,
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1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0,
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1, 0,
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};
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typedef struct
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{
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HUFF_ELEMENT *table;
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int linbits;
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int ncase;
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}
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HUFF_SETUP;
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#define no_bits 0
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#define one_shot 1
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#define no_linbits 2
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#define have_linbits 3
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#define quad_a 4
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#define quad_b 5
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static HUFF_SETUP table_look[] =
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{
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huff_table_0, 0, no_bits,
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huff_table_1, 0, one_shot,
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huff_table_2, 0, one_shot,
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huff_table_3, 0, one_shot,
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huff_table_0, 0, no_bits,
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huff_table_5, 0, one_shot,
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huff_table_6, 0, one_shot,
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huff_table_7, 0, no_linbits,
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huff_table_8, 0, no_linbits,
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huff_table_9, 0, no_linbits,
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huff_table_10, 0, no_linbits,
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huff_table_11, 0, no_linbits,
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huff_table_12, 0, no_linbits,
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huff_table_13, 0, no_linbits,
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huff_table_0, 0, no_bits,
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huff_table_15, 0, no_linbits,
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huff_table_16, 1, have_linbits,
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huff_table_16, 2, have_linbits,
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huff_table_16, 3, have_linbits,
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huff_table_16, 4, have_linbits,
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huff_table_16, 6, have_linbits,
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huff_table_16, 8, have_linbits,
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huff_table_16, 10, have_linbits,
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huff_table_16, 13, have_linbits,
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huff_table_24, 4, have_linbits,
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huff_table_24, 5, have_linbits,
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huff_table_24, 6, have_linbits,
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huff_table_24, 7, have_linbits,
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huff_table_24, 8, have_linbits,
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huff_table_24, 9, have_linbits,
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huff_table_24, 11, have_linbits,
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huff_table_24, 13, have_linbits,
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huff_table_0, 0, quad_a,
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huff_table_0, 0, quad_b,
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};
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/*========================================================*/
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void huffman(int xy[][2], int n, int ntable)
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{
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int i;
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HUFF_ELEMENT *t;
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HUFF_ELEMENT *t0;
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int linbits;
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int bits;
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int code;
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int x, y;
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if (n <= 0)
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return;
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n = n >> 1; /* huff in pairs */
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/*-------------*/
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t0 = table_look[ntable].table;
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linbits = table_look[ntable].linbits;
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switch (table_look[ntable].ncase)
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{
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default:
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/*------------------------------------------*/
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case no_bits:
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/*- table 0, no data, x=y=0--*/
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for (i = 0; i < n; i++)
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{
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xy[i][0] = 0;
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xy[i][1] = 0;
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}
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return;
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/*------------------------------------------*/
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case one_shot:
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/*- single lookup, no escapes -*/
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for (i = 0; i < n; i++)
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{
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mac_bitget_check((MAXBITS + 2));
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bits = t0[0].b.signbits;
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code = mac_bitget2(bits);
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mac_bitget_purge(t0[1 + code].b.purgebits);
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x = t0[1 + code].b.x;
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y = t0[1 + code].b.y;
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if (x)
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if (mac_bitget_1bit())
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x = -x;
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if (y)
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if (mac_bitget_1bit())
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y = -y;
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xy[i][0] = x;
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xy[i][1] = y;
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if (bitget_overrun())
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break; // bad data protect
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}
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return;
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/*------------------------------------------*/
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case no_linbits:
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for (i = 0; i < n; i++)
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{
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t = t0;
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for (;;)
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{
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mac_bitget_check((MAXBITS + 2));
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bits = t[0].b.signbits;
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code = mac_bitget2(bits);
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if (t[1 + code].b.purgebits)
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break;
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t += t[1 + code].ptr; /* ptr include 1+code */
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mac_bitget_purge(bits);
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}
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mac_bitget_purge(t[1 + code].b.purgebits);
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x = t[1 + code].b.x;
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y = t[1 + code].b.y;
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if (x)
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if (mac_bitget_1bit())
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x = -x;
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if (y)
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if (mac_bitget_1bit())
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y = -y;
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xy[i][0] = x;
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xy[i][1] = y;
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if (bitget_overrun())
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break; // bad data protect
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}
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return;
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/*------------------------------------------*/
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case have_linbits:
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for (i = 0; i < n; i++)
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{
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t = t0;
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for (;;)
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{
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bits = t[0].b.signbits;
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code = bitget2(bits);
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if (t[1 + code].b.purgebits)
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break;
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t += t[1 + code].ptr; /* ptr includes 1+code */
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mac_bitget_purge(bits);
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}
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mac_bitget_purge(t[1 + code].b.purgebits);
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x = t[1 + code].b.x;
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y = t[1 + code].b.y;
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if (x == 15)
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x += bitget_lb(linbits);
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if (x)
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if (mac_bitget_1bit())
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x = -x;
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if (y == 15)
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y += bitget_lb(linbits);
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if (y)
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if (mac_bitget_1bit())
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y = -y;
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xy[i][0] = x;
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xy[i][1] = y;
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if (bitget_overrun())
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break; // bad data protect
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}
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return;
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}
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/*--- end switch ---*/
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}
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int huffman_quad(int vwxy[][4], int n, int nbits, int ntable)
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{
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int i;
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int code;
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int x, y, v, w;
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int tmp;
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int i_non_zero, tmp_nz;
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tmp_nz = 15;
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i_non_zero = -1;
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n = n >> 2; /* huff in quads */
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if (ntable)
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goto case_quad_b;
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/* case_quad_a: */
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for (i = 0; i < n; i++)
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{
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if (nbits <= 0)
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break;
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mac_bitget_check(10);
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code = mac_bitget2(6);
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nbits -= quad_table_a[code][0];
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mac_bitget_purge(quad_table_a[code][0]);
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tmp = quad_table_a[code][1];
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if (tmp)
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{
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i_non_zero = i;
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tmp_nz = tmp;
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}
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v = (tmp >> 3) & 1;
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w = (tmp >> 2) & 1;
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x = (tmp >> 1) & 1;
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y = tmp & 1;
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if (v)
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{
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if (mac_bitget_1bit())
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v = -v;
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nbits--;
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}
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if (w)
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{
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if (mac_bitget_1bit())
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w = -w;
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nbits--;
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}
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if (x)
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{
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if (mac_bitget_1bit())
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x = -x;
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nbits--;
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}
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if (y)
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{
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if (mac_bitget_1bit())
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y = -y;
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nbits--;
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}
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vwxy[i][0] = v;
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vwxy[i][1] = w;
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vwxy[i][2] = x;
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vwxy[i][3] = y;
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if (bitget_overrun())
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break; // bad data protect
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}
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if (nbits < 0)
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{
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i--;
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vwxy[i][0] = 0;
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vwxy[i][1] = 0;
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vwxy[i][2] = 0;
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vwxy[i][3] = 0;
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}
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i_non_zero = (i_non_zero + 1) << 2;
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if ((tmp_nz & 3) == 0)
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i_non_zero -= 2;
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return i_non_zero;
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/*--------------------*/
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case_quad_b:
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for (i = 0; i < n; i++)
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{
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if (nbits < 4)
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break;
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nbits -= 4;
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mac_bitget_check(8);
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tmp = mac_bitget(4) ^ 15; /* one's complement of bitstream */
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if (tmp)
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{
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i_non_zero = i;
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tmp_nz = tmp;
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}
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v = (tmp >> 3) & 1;
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w = (tmp >> 2) & 1;
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x = (tmp >> 1) & 1;
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y = tmp & 1;
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if (v)
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{
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if (mac_bitget_1bit())
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v = -v;
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nbits--;
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}
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if (w)
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{
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if (mac_bitget_1bit())
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w = -w;
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nbits--;
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}
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if (x)
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{
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if (mac_bitget_1bit())
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x = -x;
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nbits--;
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}
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if (y)
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{
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if (mac_bitget_1bit())
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y = -y;
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nbits--;
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}
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vwxy[i][0] = v;
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vwxy[i][1] = w;
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vwxy[i][2] = x;
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vwxy[i][3] = y;
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if (bitget_overrun())
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break; // bad data protect
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}
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if (nbits < 0)
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{
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i--;
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vwxy[i][0] = 0;
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vwxy[i][1] = 0;
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vwxy[i][2] = 0;
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vwxy[i][3] = 0;
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}
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i_non_zero = (i_non_zero + 1) << 2;
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if ((tmp_nz & 3) == 0)
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i_non_zero -= 2;
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return i_non_zero; /* return non-zero sample (to nearest pair) */
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}
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