flacdsp_lpc_template.c (5112B)
1 /* 2 * This file is part of FFmpeg. 3 * 4 * FFmpeg is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU Lesser General Public 6 * License as published by the Free Software Foundation; either 7 * version 2.1 of the License, or (at your option) any later version. 8 * 9 * FFmpeg is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 12 * Lesser General Public License for more details. 13 * 14 * You should have received a copy of the GNU Lesser General Public 15 * License along with FFmpeg; if not, write to the Free Software 16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 17 */ 18 19 #include <stdint.h> 20 #include "libavutil/common.h" 21 #include "mathops.h" 22 23 #undef FUNC 24 #undef sum_type 25 #undef MUL 26 #undef CLIP 27 #undef FSUF 28 29 #define FUNC(n) AV_JOIN(n ## _, SAMPLE_SIZE) 30 31 #if SAMPLE_SIZE == 32 32 # define sum_type int64_t 33 # define MUL(a, b) MUL64(a, b) 34 # define CLIP(x) av_clipl_int32(x) 35 #else 36 # define sum_type int32_t 37 # define MUL(a, b) ((a) * (b)) 38 # define CLIP(x) (x) 39 #endif 40 41 #define LPC1(x) { \ 42 int c = coefs[(x)-1]; \ 43 p0 += MUL(c, s); \ 44 s = smp[i-(x)+1]; \ 45 p1 += MUL(c, s); \ 46 } 47 48 static av_always_inline void FUNC(lpc_encode_unrolled)(int32_t *res, 49 const int32_t *smp, int len, int order, 50 const int32_t *coefs, int shift, int big) 51 { 52 int i; 53 for (i = order; i < len; i += 2) { 54 int s = smp[i-order]; 55 sum_type p0 = 0, p1 = 0; 56 if (big) { 57 switch (order) { 58 case 32: LPC1(32) 59 case 31: LPC1(31) 60 case 30: LPC1(30) 61 case 29: LPC1(29) 62 case 28: LPC1(28) 63 case 27: LPC1(27) 64 case 26: LPC1(26) 65 case 25: LPC1(25) 66 case 24: LPC1(24) 67 case 23: LPC1(23) 68 case 22: LPC1(22) 69 case 21: LPC1(21) 70 case 20: LPC1(20) 71 case 19: LPC1(19) 72 case 18: LPC1(18) 73 case 17: LPC1(17) 74 case 16: LPC1(16) 75 case 15: LPC1(15) 76 case 14: LPC1(14) 77 case 13: LPC1(13) 78 case 12: LPC1(12) 79 case 11: LPC1(11) 80 case 10: LPC1(10) 81 case 9: LPC1( 9) 82 LPC1( 8) 83 LPC1( 7) 84 LPC1( 6) 85 LPC1( 5) 86 LPC1( 4) 87 LPC1( 3) 88 LPC1( 2) 89 LPC1( 1) 90 } 91 } else { 92 switch (order) { 93 case 8: LPC1( 8) 94 case 7: LPC1( 7) 95 case 6: LPC1( 6) 96 case 5: LPC1( 5) 97 case 4: LPC1( 4) 98 case 3: LPC1( 3) 99 case 2: LPC1( 2) 100 case 1: LPC1( 1) 101 } 102 } 103 res[i ] = smp[i ] - CLIP(p0 >> shift); 104 res[i+1] = smp[i+1] - CLIP(p1 >> shift); 105 } 106 } 107 108 static void FUNC(flac_lpc_encode_c)(int32_t *res, const int32_t *smp, int len, 109 int order, const int32_t *coefs, int shift) 110 { 111 int i; 112 for (i = 0; i < order; i++) 113 res[i] = smp[i]; 114 #if CONFIG_SMALL 115 for (i = order; i < len; i += 2) { 116 int j; 117 int s = smp[i]; 118 sum_type p0 = 0, p1 = 0; 119 for (j = 0; j < order; j++) { 120 int c = coefs[j]; 121 p1 += MUL(c, s); 122 s = smp[i-j-1]; 123 p0 += MUL(c, s); 124 } 125 res[i ] = smp[i ] - CLIP(p0 >> shift); 126 res[i+1] = smp[i+1] - CLIP(p1 >> shift); 127 } 128 #else 129 switch (order) { 130 case 1: FUNC(lpc_encode_unrolled)(res, smp, len, 1, coefs, shift, 0); break; 131 case 2: FUNC(lpc_encode_unrolled)(res, smp, len, 2, coefs, shift, 0); break; 132 case 3: FUNC(lpc_encode_unrolled)(res, smp, len, 3, coefs, shift, 0); break; 133 case 4: FUNC(lpc_encode_unrolled)(res, smp, len, 4, coefs, shift, 0); break; 134 case 5: FUNC(lpc_encode_unrolled)(res, smp, len, 5, coefs, shift, 0); break; 135 case 6: FUNC(lpc_encode_unrolled)(res, smp, len, 6, coefs, shift, 0); break; 136 case 7: FUNC(lpc_encode_unrolled)(res, smp, len, 7, coefs, shift, 0); break; 137 case 8: FUNC(lpc_encode_unrolled)(res, smp, len, 8, coefs, shift, 0); break; 138 default: FUNC(lpc_encode_unrolled)(res, smp, len, order, coefs, shift, 1); break; 139 } 140 #endif 141 } 142 143 /* Comment for clarity/de-obfuscation. 144 * 145 * for (int i = order; i < len; i++) { 146 * int32_t p = 0; 147 * for (int j = 0; j < order; j++) { 148 * int c = coefs[j]; 149 * int s = smp[(i-1)-j]; 150 * p += c*s; 151 * } 152 * res[i] = smp[i] - (p >> shift); 153 * } 154 * 155 * The CONFIG_SMALL code above simplifies to this, in the case of SAMPLE_SIZE 156 * not being equal to 32 (at the present time that means for 16-bit audio). The 157 * code above does 2 samples per iteration. Commit bfdd5bc (made all the way 158 * back in 2007) says that way is faster. 159 */