1 ; 2 ; Copyright (c) 2010 The Webm project authors. All Rights Reserved. 3 ; 4 ; Use of this source code is governed by a BSD-style license 5 ; that can be found in the LICENSE file in the root of the source 6 ; tree. An additional intellectual property rights grant can be found 7 ; in the file PATENTS. All contributing project authors may 8 ; be found in the AUTHORS file in the root of the source tree. 9 ; 10 11 12 EXPORT |idct_dequant_dc_full_2x_neon| 13 ARM 14 REQUIRE8 15 PRESERVE8 16 17 AREA ||.text||, CODE, READONLY, ALIGN=2 18 ;void idct_dequant_dc_full_2x_neon(short *q, short *dq, unsigned char *pre, 19 ; unsigned char *dst, int stride, short *dc); 20 ; r0 *q, 21 ; r1 *dq, 22 ; r2 *pre 23 ; r3 *dst 24 ; sp stride 25 ; sp+4 *dc 26 |idct_dequant_dc_full_2x_neon| PROC 27 vld1.16 {q0, q1}, [r1] ; dq (same l/r) 28 vld1.16 {q2, q3}, [r0] ; l q 29 mov r1, #16 ; pitch 30 add r0, r0, #32 31 vld1.16 {q4, q5}, [r0] ; r q 32 add r12, r2, #4 33 ; interleave the predictors 34 vld1.32 {d28[0]}, [r2], r1 ; l pre 35 vld1.32 {d28[1]}, [r12], r1 ; r pre 36 vld1.32 {d29[0]}, [r2], r1 37 vld1.32 {d29[1]}, [r12], r1 38 vld1.32 {d30[0]}, [r2], r1 39 vld1.32 {d30[1]}, [r12], r1 40 vld1.32 {d31[0]}, [r2] 41 ldr r1, [sp, #4] 42 vld1.32 {d31[1]}, [r12] 43 44 ldr r2, _CONSTANTS_ 45 46 ldrh r12, [r1], #2 ; lo *dc 47 ldrh r1, [r1] ; hi *dc 48 49 ; dequant: q[i] = q[i] * dq[i] 50 vmul.i16 q2, q2, q0 51 vmul.i16 q3, q3, q1 52 vmul.i16 q4, q4, q0 53 vmul.i16 q5, q5, q1 54 55 ; move dc up to neon and overwrite first element 56 vmov.16 d4[0], r12 57 vmov.16 d8[0], r1 58 59 vld1.16 {d0}, [r2] 60 61 ; q2: l0r0 q3: l8r8 62 ; q4: l4r4 q5: l12r12 63 vswp d5, d8 64 vswp d7, d10 65 66 ; _CONSTANTS_ * 4,12 >> 16 67 ; q6: 4 * sinpi : c1/temp1 68 ; q7: 12 * sinpi : d1/temp2 69 ; q8: 4 * cospi 70 ; q9: 12 * cospi 71 vqdmulh.s16 q6, q4, d0[2] ; sinpi8sqrt2 72 vqdmulh.s16 q7, q5, d0[2] 73 vqdmulh.s16 q8, q4, d0[0] ; cospi8sqrt2minus1 74 vqdmulh.s16 q9, q5, d0[0] 75 76 vqadd.s16 q10, q2, q3 ; a1 = 0 + 8 77 vqsub.s16 q11, q2, q3 ; b1 = 0 - 8 78 79 ; vqdmulh only accepts signed values. this was a problem because 80 ; our constant had the high bit set, and was treated as a negative value. 81 ; vqdmulh also doubles the value before it shifts by 16. we need to 82 ; compensate for this. in the case of sinpi8sqrt2, the lowest bit is 0, 83 ; so we can shift the constant without losing precision. this avoids 84 ; shift again afterward, but also avoids the sign issue. win win! 85 ; for cospi8sqrt2minus1 the lowest bit is 1, so we lose precision if we 86 ; pre-shift it 87 vshr.s16 q8, q8, #1 88 vshr.s16 q9, q9, #1 89 90 ; q4: 4 + 4 * cospi : d1/temp1 91 ; q5: 12 + 12 * cospi : c1/temp2 92 vqadd.s16 q4, q4, q8 93 vqadd.s16 q5, q5, q9 94 95 ; c1 = temp1 - temp2 96 ; d1 = temp1 + temp2 97 vqsub.s16 q2, q6, q5 98 vqadd.s16 q3, q4, q7 99 100 ; [0]: a1+d1 101 ; [1]: b1+c1 102 ; [2]: b1-c1 103 ; [3]: a1-d1 104 vqadd.s16 q4, q10, q3 105 vqadd.s16 q5, q11, q2 106 vqsub.s16 q6, q11, q2 107 vqsub.s16 q7, q10, q3 108 109 ; rotate 110 vtrn.32 q4, q6 111 vtrn.32 q5, q7 112 vtrn.16 q4, q5 113 vtrn.16 q6, q7 114 ; idct loop 2 115 ; q4: l 0, 4, 8,12 r 0, 4, 8,12 116 ; q5: l 1, 5, 9,13 r 1, 5, 9,13 117 ; q6: l 2, 6,10,14 r 2, 6,10,14 118 ; q7: l 3, 7,11,15 r 3, 7,11,15 119 120 ; q8: 1 * sinpi : c1/temp1 121 ; q9: 3 * sinpi : d1/temp2 122 ; q10: 1 * cospi 123 ; q11: 3 * cospi 124 vqdmulh.s16 q8, q5, d0[2] ; sinpi8sqrt2 125 vqdmulh.s16 q9, q7, d0[2] 126 vqdmulh.s16 q10, q5, d0[0] ; cospi8sqrt2minus1 127 vqdmulh.s16 q11, q7, d0[0] 128 129 vqadd.s16 q2, q4, q6 ; a1 = 0 + 2 130 vqsub.s16 q3, q4, q6 ; b1 = 0 - 2 131 132 ; see note on shifting above 133 vshr.s16 q10, q10, #1 134 vshr.s16 q11, q11, #1 135 136 ; q10: 1 + 1 * cospi : d1/temp1 137 ; q11: 3 + 3 * cospi : c1/temp2 138 vqadd.s16 q10, q5, q10 139 vqadd.s16 q11, q7, q11 140 141 ; q8: c1 = temp1 - temp2 142 ; q9: d1 = temp1 + temp2 143 vqsub.s16 q8, q8, q11 144 vqadd.s16 q9, q10, q9 145 146 ; a1+d1 147 ; b1+c1 148 ; b1-c1 149 ; a1-d1 150 vqadd.s16 q4, q2, q9 151 vqadd.s16 q5, q3, q8 152 vqsub.s16 q6, q3, q8 153 vqsub.s16 q7, q2, q9 154 155 ; +4 >> 3 (rounding) 156 vrshr.s16 q4, q4, #3 ; lo 157 vrshr.s16 q5, q5, #3 158 vrshr.s16 q6, q6, #3 ; hi 159 vrshr.s16 q7, q7, #3 160 161 vtrn.32 q4, q6 162 vtrn.32 q5, q7 163 vtrn.16 q4, q5 164 vtrn.16 q6, q7 165 166 ; adding pre 167 ; input is still packed. pre was read interleaved 168 vaddw.u8 q4, q4, d28 169 vaddw.u8 q5, q5, d29 170 vaddw.u8 q6, q6, d30 171 vaddw.u8 q7, q7, d31 172 173 vmov.i16 q14, #0 174 vmov q15, q14 175 vst1.16 {q14, q15}, [r0] ; write over high input 176 sub r0, r0, #32 177 vst1.16 {q14, q15}, [r0] ; write over low input 178 179 ;saturate and narrow 180 vqmovun.s16 d0, q4 ; lo 181 vqmovun.s16 d1, q5 182 vqmovun.s16 d2, q6 ; hi 183 vqmovun.s16 d3, q7 184 185 ldr r1, [sp] ; stride 186 add r2, r3, #4 ; hi 187 vst1.32 {d0[0]}, [r3], r1 ; lo 188 vst1.32 {d0[1]}, [r2], r1 ; hi 189 vst1.32 {d1[0]}, [r3], r1 190 vst1.32 {d1[1]}, [r2], r1 191 vst1.32 {d2[0]}, [r3], r1 192 vst1.32 {d2[1]}, [r2], r1 193 vst1.32 {d3[0]}, [r3] 194 vst1.32 {d3[1]}, [r2] 195 196 bx lr 197 198 ENDP ; |idct_dequant_dc_full_2x_neon| 199 200 ; Constant Pool 201 _CONSTANTS_ DCD cospi8sqrt2minus1 202 cospi8sqrt2minus1 DCD 0x4e7b 203 ; because the lowest bit in 0x8a8c is 0, we can pre-shift this 204 sinpi8sqrt2 DCD 0x4546 205 206 END 207
