ref: 2221ec88d54c307d5f7496d1ff5cf6fd029e0b1f
dir: /vp9/encoder/x86/vp9_dct_ssse3.c/
/*
* Copyright (c) 2014 The WebM project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include <assert.h>
#include <tmmintrin.h> // SSSE3
#include "./vp9_rtcd.h"
#include "./vpx_config.h"
#include "vpx_dsp/vpx_dsp_common.h"
#include "vpx_dsp/x86/bitdepth_conversion_sse2.h"
#include "vpx_dsp/x86/inv_txfm_sse2.h"
#include "vpx_dsp/x86/txfm_common_sse2.h"
void vp9_fdct8x8_quant_ssse3(const int16_t *input, int stride,
tran_low_t *coeff_ptr, intptr_t n_coeffs,
int skip_block, const int16_t *round_ptr,
const int16_t *quant_ptr, tran_low_t *qcoeff_ptr,
tran_low_t *dqcoeff_ptr,
const int16_t *dequant_ptr, uint16_t *eob_ptr,
const int16_t *scan, const int16_t *iscan) {
__m128i zero;
int pass;
// Constants
// When we use them, in one case, they are all the same. In all others
// it's a pair of them that we need to repeat four times. This is done
// by constructing the 32 bit constant corresponding to that pair.
const __m128i k__dual_p16_p16 = dual_set_epi16(23170, 23170);
const __m128i k__cospi_p16_p16 = _mm_set1_epi16(cospi_16_64);
const __m128i k__cospi_p16_m16 = pair_set_epi16(cospi_16_64, -cospi_16_64);
const __m128i k__cospi_p24_p08 = pair_set_epi16(cospi_24_64, cospi_8_64);
const __m128i k__cospi_m08_p24 = pair_set_epi16(-cospi_8_64, cospi_24_64);
const __m128i k__cospi_p28_p04 = pair_set_epi16(cospi_28_64, cospi_4_64);
const __m128i k__cospi_m04_p28 = pair_set_epi16(-cospi_4_64, cospi_28_64);
const __m128i k__cospi_p12_p20 = pair_set_epi16(cospi_12_64, cospi_20_64);
const __m128i k__cospi_m20_p12 = pair_set_epi16(-cospi_20_64, cospi_12_64);
const __m128i k__DCT_CONST_ROUNDING = _mm_set1_epi32(DCT_CONST_ROUNDING);
// Load input
__m128i in0 = _mm_load_si128((const __m128i *)(input + 0 * stride));
__m128i in1 = _mm_load_si128((const __m128i *)(input + 1 * stride));
__m128i in2 = _mm_load_si128((const __m128i *)(input + 2 * stride));
__m128i in3 = _mm_load_si128((const __m128i *)(input + 3 * stride));
__m128i in4 = _mm_load_si128((const __m128i *)(input + 4 * stride));
__m128i in5 = _mm_load_si128((const __m128i *)(input + 5 * stride));
__m128i in6 = _mm_load_si128((const __m128i *)(input + 6 * stride));
__m128i in7 = _mm_load_si128((const __m128i *)(input + 7 * stride));
__m128i *in[8];
int index = 0;
(void)scan;
(void)coeff_ptr;
// Pre-condition input (shift by two)
in0 = _mm_slli_epi16(in0, 2);
in1 = _mm_slli_epi16(in1, 2);
in2 = _mm_slli_epi16(in2, 2);
in3 = _mm_slli_epi16(in3, 2);
in4 = _mm_slli_epi16(in4, 2);
in5 = _mm_slli_epi16(in5, 2);
in6 = _mm_slli_epi16(in6, 2);
in7 = _mm_slli_epi16(in7, 2);
in[0] = &in0;
in[1] = &in1;
in[2] = &in2;
in[3] = &in3;
in[4] = &in4;
in[5] = &in5;
in[6] = &in6;
in[7] = &in7;
// We do two passes, first the columns, then the rows. The results of the
// first pass are transposed so that the same column code can be reused. The
// results of the second pass are also transposed so that the rows (processed
// as columns) are put back in row positions.
for (pass = 0; pass < 2; pass++) {
// To store results of each pass before the transpose.
__m128i res0, res1, res2, res3, res4, res5, res6, res7;
// Add/subtract
const __m128i q0 = _mm_add_epi16(in0, in7);
const __m128i q1 = _mm_add_epi16(in1, in6);
const __m128i q2 = _mm_add_epi16(in2, in5);
const __m128i q3 = _mm_add_epi16(in3, in4);
const __m128i q4 = _mm_sub_epi16(in3, in4);
const __m128i q5 = _mm_sub_epi16(in2, in5);
const __m128i q6 = _mm_sub_epi16(in1, in6);
const __m128i q7 = _mm_sub_epi16(in0, in7);
// Work on first four results
{
// Add/subtract
const __m128i r0 = _mm_add_epi16(q0, q3);
const __m128i r1 = _mm_add_epi16(q1, q2);
const __m128i r2 = _mm_sub_epi16(q1, q2);
const __m128i r3 = _mm_sub_epi16(q0, q3);
// Interleave to do the multiply by constants which gets us into 32bits
const __m128i t0 = _mm_unpacklo_epi16(r0, r1);
const __m128i t1 = _mm_unpackhi_epi16(r0, r1);
const __m128i t2 = _mm_unpacklo_epi16(r2, r3);
const __m128i t3 = _mm_unpackhi_epi16(r2, r3);
const __m128i u0 = _mm_madd_epi16(t0, k__cospi_p16_p16);
const __m128i u1 = _mm_madd_epi16(t1, k__cospi_p16_p16);
const __m128i u2 = _mm_madd_epi16(t0, k__cospi_p16_m16);
const __m128i u3 = _mm_madd_epi16(t1, k__cospi_p16_m16);
const __m128i u4 = _mm_madd_epi16(t2, k__cospi_p24_p08);
const __m128i u5 = _mm_madd_epi16(t3, k__cospi_p24_p08);
const __m128i u6 = _mm_madd_epi16(t2, k__cospi_m08_p24);
const __m128i u7 = _mm_madd_epi16(t3, k__cospi_m08_p24);
// dct_const_round_shift
const __m128i v0 = _mm_add_epi32(u0, k__DCT_CONST_ROUNDING);
const __m128i v1 = _mm_add_epi32(u1, k__DCT_CONST_ROUNDING);
const __m128i v2 = _mm_add_epi32(u2, k__DCT_CONST_ROUNDING);
const __m128i v3 = _mm_add_epi32(u3, k__DCT_CONST_ROUNDING);
const __m128i v4 = _mm_add_epi32(u4, k__DCT_CONST_ROUNDING);
const __m128i v5 = _mm_add_epi32(u5, k__DCT_CONST_ROUNDING);
const __m128i v6 = _mm_add_epi32(u6, k__DCT_CONST_ROUNDING);
const __m128i v7 = _mm_add_epi32(u7, k__DCT_CONST_ROUNDING);
const __m128i w0 = _mm_srai_epi32(v0, DCT_CONST_BITS);
const __m128i w1 = _mm_srai_epi32(v1, DCT_CONST_BITS);
const __m128i w2 = _mm_srai_epi32(v2, DCT_CONST_BITS);
const __m128i w3 = _mm_srai_epi32(v3, DCT_CONST_BITS);
const __m128i w4 = _mm_srai_epi32(v4, DCT_CONST_BITS);
const __m128i w5 = _mm_srai_epi32(v5, DCT_CONST_BITS);
const __m128i w6 = _mm_srai_epi32(v6, DCT_CONST_BITS);
const __m128i w7 = _mm_srai_epi32(v7, DCT_CONST_BITS);
// Combine
res0 = _mm_packs_epi32(w0, w1);
res4 = _mm_packs_epi32(w2, w3);
res2 = _mm_packs_epi32(w4, w5);
res6 = _mm_packs_epi32(w6, w7);
}
// Work on next four results
{
// Interleave to do the multiply by constants which gets us into 32bits
const __m128i d0 = _mm_sub_epi16(q6, q5);
const __m128i d1 = _mm_add_epi16(q6, q5);
const __m128i r0 = _mm_mulhrs_epi16(d0, k__dual_p16_p16);
const __m128i r1 = _mm_mulhrs_epi16(d1, k__dual_p16_p16);
// Add/subtract
const __m128i x0 = _mm_add_epi16(q4, r0);
const __m128i x1 = _mm_sub_epi16(q4, r0);
const __m128i x2 = _mm_sub_epi16(q7, r1);
const __m128i x3 = _mm_add_epi16(q7, r1);
// Interleave to do the multiply by constants which gets us into 32bits
const __m128i t0 = _mm_unpacklo_epi16(x0, x3);
const __m128i t1 = _mm_unpackhi_epi16(x0, x3);
const __m128i t2 = _mm_unpacklo_epi16(x1, x2);
const __m128i t3 = _mm_unpackhi_epi16(x1, x2);
const __m128i u0 = _mm_madd_epi16(t0, k__cospi_p28_p04);
const __m128i u1 = _mm_madd_epi16(t1, k__cospi_p28_p04);
const __m128i u2 = _mm_madd_epi16(t0, k__cospi_m04_p28);
const __m128i u3 = _mm_madd_epi16(t1, k__cospi_m04_p28);
const __m128i u4 = _mm_madd_epi16(t2, k__cospi_p12_p20);
const __m128i u5 = _mm_madd_epi16(t3, k__cospi_p12_p20);
const __m128i u6 = _mm_madd_epi16(t2, k__cospi_m20_p12);
const __m128i u7 = _mm_madd_epi16(t3, k__cospi_m20_p12);
// dct_const_round_shift
const __m128i v0 = _mm_add_epi32(u0, k__DCT_CONST_ROUNDING);
const __m128i v1 = _mm_add_epi32(u1, k__DCT_CONST_ROUNDING);
const __m128i v2 = _mm_add_epi32(u2, k__DCT_CONST_ROUNDING);
const __m128i v3 = _mm_add_epi32(u3, k__DCT_CONST_ROUNDING);
const __m128i v4 = _mm_add_epi32(u4, k__DCT_CONST_ROUNDING);
const __m128i v5 = _mm_add_epi32(u5, k__DCT_CONST_ROUNDING);
const __m128i v6 = _mm_add_epi32(u6, k__DCT_CONST_ROUNDING);
const __m128i v7 = _mm_add_epi32(u7, k__DCT_CONST_ROUNDING);
const __m128i w0 = _mm_srai_epi32(v0, DCT_CONST_BITS);
const __m128i w1 = _mm_srai_epi32(v1, DCT_CONST_BITS);
const __m128i w2 = _mm_srai_epi32(v2, DCT_CONST_BITS);
const __m128i w3 = _mm_srai_epi32(v3, DCT_CONST_BITS);
const __m128i w4 = _mm_srai_epi32(v4, DCT_CONST_BITS);
const __m128i w5 = _mm_srai_epi32(v5, DCT_CONST_BITS);
const __m128i w6 = _mm_srai_epi32(v6, DCT_CONST_BITS);
const __m128i w7 = _mm_srai_epi32(v7, DCT_CONST_BITS);
// Combine
res1 = _mm_packs_epi32(w0, w1);
res7 = _mm_packs_epi32(w2, w3);
res5 = _mm_packs_epi32(w4, w5);
res3 = _mm_packs_epi32(w6, w7);
}
// Transpose the 8x8.
{
// 00 01 02 03 04 05 06 07
// 10 11 12 13 14 15 16 17
// 20 21 22 23 24 25 26 27
// 30 31 32 33 34 35 36 37
// 40 41 42 43 44 45 46 47
// 50 51 52 53 54 55 56 57
// 60 61 62 63 64 65 66 67
// 70 71 72 73 74 75 76 77
const __m128i tr0_0 = _mm_unpacklo_epi16(res0, res1);
const __m128i tr0_1 = _mm_unpacklo_epi16(res2, res3);
const __m128i tr0_2 = _mm_unpackhi_epi16(res0, res1);
const __m128i tr0_3 = _mm_unpackhi_epi16(res2, res3);
const __m128i tr0_4 = _mm_unpacklo_epi16(res4, res5);
const __m128i tr0_5 = _mm_unpacklo_epi16(res6, res7);
const __m128i tr0_6 = _mm_unpackhi_epi16(res4, res5);
const __m128i tr0_7 = _mm_unpackhi_epi16(res6, res7);
// 00 10 01 11 02 12 03 13
// 20 30 21 31 22 32 23 33
// 04 14 05 15 06 16 07 17
// 24 34 25 35 26 36 27 37
// 40 50 41 51 42 52 43 53
// 60 70 61 71 62 72 63 73
// 54 54 55 55 56 56 57 57
// 64 74 65 75 66 76 67 77
const __m128i tr1_0 = _mm_unpacklo_epi32(tr0_0, tr0_1);
const __m128i tr1_1 = _mm_unpacklo_epi32(tr0_2, tr0_3);
const __m128i tr1_2 = _mm_unpackhi_epi32(tr0_0, tr0_1);
const __m128i tr1_3 = _mm_unpackhi_epi32(tr0_2, tr0_3);
const __m128i tr1_4 = _mm_unpacklo_epi32(tr0_4, tr0_5);
const __m128i tr1_5 = _mm_unpacklo_epi32(tr0_6, tr0_7);
const __m128i tr1_6 = _mm_unpackhi_epi32(tr0_4, tr0_5);
const __m128i tr1_7 = _mm_unpackhi_epi32(tr0_6, tr0_7);
// 00 10 20 30 01 11 21 31
// 40 50 60 70 41 51 61 71
// 02 12 22 32 03 13 23 33
// 42 52 62 72 43 53 63 73
// 04 14 24 34 05 15 21 36
// 44 54 64 74 45 55 61 76
// 06 16 26 36 07 17 27 37
// 46 56 66 76 47 57 67 77
in0 = _mm_unpacklo_epi64(tr1_0, tr1_4);
in1 = _mm_unpackhi_epi64(tr1_0, tr1_4);
in2 = _mm_unpacklo_epi64(tr1_2, tr1_6);
in3 = _mm_unpackhi_epi64(tr1_2, tr1_6);
in4 = _mm_unpacklo_epi64(tr1_1, tr1_5);
in5 = _mm_unpackhi_epi64(tr1_1, tr1_5);
in6 = _mm_unpacklo_epi64(tr1_3, tr1_7);
in7 = _mm_unpackhi_epi64(tr1_3, tr1_7);
// 00 10 20 30 40 50 60 70
// 01 11 21 31 41 51 61 71
// 02 12 22 32 42 52 62 72
// 03 13 23 33 43 53 63 73
// 04 14 24 34 44 54 64 74
// 05 15 25 35 45 55 65 75
// 06 16 26 36 46 56 66 76
// 07 17 27 37 47 57 67 77
}
}
// Post-condition output and store it
{
// Post-condition (division by two)
// division of two 16 bits signed numbers using shifts
// n / 2 = (n - (n >> 15)) >> 1
const __m128i sign_in0 = _mm_srai_epi16(in0, 15);
const __m128i sign_in1 = _mm_srai_epi16(in1, 15);
const __m128i sign_in2 = _mm_srai_epi16(in2, 15);
const __m128i sign_in3 = _mm_srai_epi16(in3, 15);
const __m128i sign_in4 = _mm_srai_epi16(in4, 15);
const __m128i sign_in5 = _mm_srai_epi16(in5, 15);
const __m128i sign_in6 = _mm_srai_epi16(in6, 15);
const __m128i sign_in7 = _mm_srai_epi16(in7, 15);
in0 = _mm_sub_epi16(in0, sign_in0);
in1 = _mm_sub_epi16(in1, sign_in1);
in2 = _mm_sub_epi16(in2, sign_in2);
in3 = _mm_sub_epi16(in3, sign_in3);
in4 = _mm_sub_epi16(in4, sign_in4);
in5 = _mm_sub_epi16(in5, sign_in5);
in6 = _mm_sub_epi16(in6, sign_in6);
in7 = _mm_sub_epi16(in7, sign_in7);
in0 = _mm_srai_epi16(in0, 1);
in1 = _mm_srai_epi16(in1, 1);
in2 = _mm_srai_epi16(in2, 1);
in3 = _mm_srai_epi16(in3, 1);
in4 = _mm_srai_epi16(in4, 1);
in5 = _mm_srai_epi16(in5, 1);
in6 = _mm_srai_epi16(in6, 1);
in7 = _mm_srai_epi16(in7, 1);
}
iscan += n_coeffs;
qcoeff_ptr += n_coeffs;
dqcoeff_ptr += n_coeffs;
n_coeffs = -n_coeffs;
zero = _mm_setzero_si128();
if (!skip_block) {
__m128i eob;
__m128i round, quant, dequant, thr;
int16_t nzflag;
{
__m128i coeff0, coeff1;
// Setup global values
{
round = _mm_load_si128((const __m128i *)round_ptr);
quant = _mm_load_si128((const __m128i *)quant_ptr);
dequant = _mm_load_si128((const __m128i *)dequant_ptr);
}
{
__m128i coeff0_sign, coeff1_sign;
__m128i qcoeff0, qcoeff1;
__m128i qtmp0, qtmp1;
// Do DC and first 15 AC
coeff0 = *in[0];
coeff1 = *in[1];
// Poor man's sign extract
coeff0_sign = _mm_srai_epi16(coeff0, 15);
coeff1_sign = _mm_srai_epi16(coeff1, 15);
qcoeff0 = _mm_xor_si128(coeff0, coeff0_sign);
qcoeff1 = _mm_xor_si128(coeff1, coeff1_sign);
qcoeff0 = _mm_sub_epi16(qcoeff0, coeff0_sign);
qcoeff1 = _mm_sub_epi16(qcoeff1, coeff1_sign);
qcoeff0 = _mm_adds_epi16(qcoeff0, round);
round = _mm_unpackhi_epi64(round, round);
qcoeff1 = _mm_adds_epi16(qcoeff1, round);
qtmp0 = _mm_mulhi_epi16(qcoeff0, quant);
quant = _mm_unpackhi_epi64(quant, quant);
qtmp1 = _mm_mulhi_epi16(qcoeff1, quant);
// Reinsert signs
qcoeff0 = _mm_xor_si128(qtmp0, coeff0_sign);
qcoeff1 = _mm_xor_si128(qtmp1, coeff1_sign);
qcoeff0 = _mm_sub_epi16(qcoeff0, coeff0_sign);
qcoeff1 = _mm_sub_epi16(qcoeff1, coeff1_sign);
store_tran_low(qcoeff0, qcoeff_ptr + n_coeffs);
store_tran_low(qcoeff1, qcoeff_ptr + n_coeffs + 8);
coeff0 = _mm_mullo_epi16(qcoeff0, dequant);
dequant = _mm_unpackhi_epi64(dequant, dequant);
coeff1 = _mm_mullo_epi16(qcoeff1, dequant);
store_tran_low(coeff0, dqcoeff_ptr + n_coeffs);
store_tran_low(coeff1, dqcoeff_ptr + n_coeffs + 8);
}
{
// Scan for eob
__m128i zero_coeff0, zero_coeff1;
__m128i nzero_coeff0, nzero_coeff1;
__m128i iscan0, iscan1;
__m128i eob1;
zero_coeff0 = _mm_cmpeq_epi16(coeff0, zero);
zero_coeff1 = _mm_cmpeq_epi16(coeff1, zero);
nzero_coeff0 = _mm_cmpeq_epi16(zero_coeff0, zero);
nzero_coeff1 = _mm_cmpeq_epi16(zero_coeff1, zero);
iscan0 = _mm_load_si128((const __m128i *)(iscan + n_coeffs));
iscan1 = _mm_load_si128((const __m128i *)(iscan + n_coeffs) + 1);
// Add one to convert from indices to counts
iscan0 = _mm_sub_epi16(iscan0, nzero_coeff0);
iscan1 = _mm_sub_epi16(iscan1, nzero_coeff1);
eob = _mm_and_si128(iscan0, nzero_coeff0);
eob1 = _mm_and_si128(iscan1, nzero_coeff1);
eob = _mm_max_epi16(eob, eob1);
}
n_coeffs += 8 * 2;
}
// AC only loop
index = 2;
thr = _mm_srai_epi16(dequant, 1);
while (n_coeffs < 0) {
__m128i coeff0, coeff1;
{
__m128i coeff0_sign, coeff1_sign;
__m128i qcoeff0, qcoeff1;
__m128i qtmp0, qtmp1;
assert(index < (int)(sizeof(in) / sizeof(in[0])) - 1);
coeff0 = *in[index];
coeff1 = *in[index + 1];
// Poor man's sign extract
coeff0_sign = _mm_srai_epi16(coeff0, 15);
coeff1_sign = _mm_srai_epi16(coeff1, 15);
qcoeff0 = _mm_xor_si128(coeff0, coeff0_sign);
qcoeff1 = _mm_xor_si128(coeff1, coeff1_sign);
qcoeff0 = _mm_sub_epi16(qcoeff0, coeff0_sign);
qcoeff1 = _mm_sub_epi16(qcoeff1, coeff1_sign);
nzflag = _mm_movemask_epi8(_mm_cmpgt_epi16(qcoeff0, thr)) |
_mm_movemask_epi8(_mm_cmpgt_epi16(qcoeff1, thr));
if (nzflag) {
qcoeff0 = _mm_adds_epi16(qcoeff0, round);
qcoeff1 = _mm_adds_epi16(qcoeff1, round);
qtmp0 = _mm_mulhi_epi16(qcoeff0, quant);
qtmp1 = _mm_mulhi_epi16(qcoeff1, quant);
// Reinsert signs
qcoeff0 = _mm_xor_si128(qtmp0, coeff0_sign);
qcoeff1 = _mm_xor_si128(qtmp1, coeff1_sign);
qcoeff0 = _mm_sub_epi16(qcoeff0, coeff0_sign);
qcoeff1 = _mm_sub_epi16(qcoeff1, coeff1_sign);
store_tran_low(qcoeff0, qcoeff_ptr + n_coeffs);
store_tran_low(qcoeff1, qcoeff_ptr + n_coeffs + 8);
coeff0 = _mm_mullo_epi16(qcoeff0, dequant);
coeff1 = _mm_mullo_epi16(qcoeff1, dequant);
store_tran_low(coeff0, dqcoeff_ptr + n_coeffs);
store_tran_low(coeff1, dqcoeff_ptr + n_coeffs + 8);
} else {
// Maybe a more efficient way to store 0?
store_zero_tran_low(qcoeff_ptr + n_coeffs);
store_zero_tran_low(qcoeff_ptr + n_coeffs + 8);
store_zero_tran_low(dqcoeff_ptr + n_coeffs);
store_zero_tran_low(dqcoeff_ptr + n_coeffs + 8);
}
}
if (nzflag) {
// Scan for eob
__m128i zero_coeff0, zero_coeff1;
__m128i nzero_coeff0, nzero_coeff1;
__m128i iscan0, iscan1;
__m128i eob0, eob1;
zero_coeff0 = _mm_cmpeq_epi16(coeff0, zero);
zero_coeff1 = _mm_cmpeq_epi16(coeff1, zero);
nzero_coeff0 = _mm_cmpeq_epi16(zero_coeff0, zero);
nzero_coeff1 = _mm_cmpeq_epi16(zero_coeff1, zero);
iscan0 = _mm_load_si128((const __m128i *)(iscan + n_coeffs));
iscan1 = _mm_load_si128((const __m128i *)(iscan + n_coeffs) + 1);
// Add one to convert from indices to counts
iscan0 = _mm_sub_epi16(iscan0, nzero_coeff0);
iscan1 = _mm_sub_epi16(iscan1, nzero_coeff1);
eob0 = _mm_and_si128(iscan0, nzero_coeff0);
eob1 = _mm_and_si128(iscan1, nzero_coeff1);
eob0 = _mm_max_epi16(eob0, eob1);
eob = _mm_max_epi16(eob, eob0);
}
n_coeffs += 8 * 2;
index += 2;
}
// Accumulate EOB
{
__m128i eob_shuffled;
eob_shuffled = _mm_shuffle_epi32(eob, 0xe);
eob = _mm_max_epi16(eob, eob_shuffled);
eob_shuffled = _mm_shufflelo_epi16(eob, 0xe);
eob = _mm_max_epi16(eob, eob_shuffled);
eob_shuffled = _mm_shufflelo_epi16(eob, 0x1);
eob = _mm_max_epi16(eob, eob_shuffled);
*eob_ptr = _mm_extract_epi16(eob, 1);
}
} else {
do {
store_zero_tran_low(dqcoeff_ptr + n_coeffs);
store_zero_tran_low(dqcoeff_ptr + n_coeffs + 8);
store_zero_tran_low(qcoeff_ptr + n_coeffs);
store_zero_tran_low(qcoeff_ptr + n_coeffs + 8);
n_coeffs += 8 * 2;
} while (n_coeffs < 0);
*eob_ptr = 0;
}
}