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_full_2x_neon| 13 ARM 14 REQUIRE8 15 PRESERVE8 16 17 AREA ||.text||, CODE, READONLY, ALIGN=2 18 ;void idct_dequant_full_2x_neon(short *q, short *dq, 19 ; unsigned char *dst, int stride); 20 ; r0 *q, 21 ; r1 *dq, 22 ; r2 *dst 23 ; r3 stride 24 |idct_dequant_full_2x_neon| PROC 25 vld1.16 {q0, q1}, [r1] ; dq (same l/r) 26 vld1.16 {q2, q3}, [r0] ; l q 27 add r0, r0, #32 28 vld1.16 {q4, q5}, [r0] ; r q 29 add r12, r2, #4 30 31 ; interleave the predictors 32 vld1.32 {d28[0]}, [r2], r3 ; l pre 33 vld1.32 {d28[1]}, [r12], r3 ; r pre 34 vld1.32 {d29[0]}, [r2], r3 35 vld1.32 {d29[1]}, [r12], r3 36 vld1.32 {d30[0]}, [r2], r3 37 vld1.32 {d30[1]}, [r12], r3 38 vld1.32 {d31[0]}, [r2], r3 39 vld1.32 {d31[1]}, [r12] 40 41 adr r1, cospi8sqrt2minus1 ; pointer to the first constant 42 43 ; dequant: q[i] = q[i] * dq[i] 44 vmul.i16 q2, q2, q0 45 vmul.i16 q3, q3, q1 46 vmul.i16 q4, q4, q0 47 vmul.i16 q5, q5, q1 48 49 vld1.16 {d0}, [r1] 50 51 ; q2: l0r0 q3: l8r8 52 ; q4: l4r4 q5: l12r12 53 vswp d5, d8 54 vswp d7, d10 55 56 ; _CONSTANTS_ * 4,12 >> 16 57 ; q6: 4 * sinpi : c1/temp1 58 ; q7: 12 * sinpi : d1/temp2 59 ; q8: 4 * cospi 60 ; q9: 12 * cospi 61 vqdmulh.s16 q6, q4, d0[2] ; sinpi8sqrt2 62 vqdmulh.s16 q7, q5, d0[2] 63 vqdmulh.s16 q8, q4, d0[0] ; cospi8sqrt2minus1 64 vqdmulh.s16 q9, q5, d0[0] 65 66 vqadd.s16 q10, q2, q3 ; a1 = 0 + 8 67 vqsub.s16 q11, q2, q3 ; b1 = 0 - 8 68 69 ; vqdmulh only accepts signed values. this was a problem because 70 ; our constant had the high bit set, and was treated as a negative value. 71 ; vqdmulh also doubles the value before it shifts by 16. we need to 72 ; compensate for this. in the case of sinpi8sqrt2, the lowest bit is 0, 73 ; so we can shift the constant without losing precision. this avoids 74 ; shift again afterward, but also avoids the sign issue. win win! 75 ; for cospi8sqrt2minus1 the lowest bit is 1, so we lose precision if we 76 ; pre-shift it 77 vshr.s16 q8, q8, #1 78 vshr.s16 q9, q9, #1 79 80 ; q4: 4 + 4 * cospi : d1/temp1 81 ; q5: 12 + 12 * cospi : c1/temp2 82 vqadd.s16 q4, q4, q8 83 vqadd.s16 q5, q5, q9 84 85 ; c1 = temp1 - temp2 86 ; d1 = temp1 + temp2 87 vqsub.s16 q2, q6, q5 88 vqadd.s16 q3, q4, q7 89 90 ; [0]: a1+d1 91 ; [1]: b1+c1 92 ; [2]: b1-c1 93 ; [3]: a1-d1 94 vqadd.s16 q4, q10, q3 95 vqadd.s16 q5, q11, q2 96 vqsub.s16 q6, q11, q2 97 vqsub.s16 q7, q10, q3 98 99 ; rotate 100 vtrn.32 q4, q6 101 vtrn.32 q5, q7 102 vtrn.16 q4, q5 103 vtrn.16 q6, q7 104 ; idct loop 2 105 ; q4: l 0, 4, 8,12 r 0, 4, 8,12 106 ; q5: l 1, 5, 9,13 r 1, 5, 9,13 107 ; q6: l 2, 6,10,14 r 2, 6,10,14 108 ; q7: l 3, 7,11,15 r 3, 7,11,15 109 110 ; q8: 1 * sinpi : c1/temp1 111 ; q9: 3 * sinpi : d1/temp2 112 ; q10: 1 * cospi 113 ; q11: 3 * cospi 114 vqdmulh.s16 q8, q5, d0[2] ; sinpi8sqrt2 115 vqdmulh.s16 q9, q7, d0[2] 116 vqdmulh.s16 q10, q5, d0[0] ; cospi8sqrt2minus1 117 vqdmulh.s16 q11, q7, d0[0] 118 119 vqadd.s16 q2, q4, q6 ; a1 = 0 + 2 120 vqsub.s16 q3, q4, q6 ; b1 = 0 - 2 121 122 ; see note on shifting above 123 vshr.s16 q10, q10, #1 124 vshr.s16 q11, q11, #1 125 126 ; q10: 1 + 1 * cospi : d1/temp1 127 ; q11: 3 + 3 * cospi : c1/temp2 128 vqadd.s16 q10, q5, q10 129 vqadd.s16 q11, q7, q11 130 131 ; q8: c1 = temp1 - temp2 132 ; q9: d1 = temp1 + temp2 133 vqsub.s16 q8, q8, q11 134 vqadd.s16 q9, q10, q9 135 136 ; a1+d1 137 ; b1+c1 138 ; b1-c1 139 ; a1-d1 140 vqadd.s16 q4, q2, q9 141 vqadd.s16 q5, q3, q8 142 vqsub.s16 q6, q3, q8 143 vqsub.s16 q7, q2, q9 144 145 ; +4 >> 3 (rounding) 146 vrshr.s16 q4, q4, #3 ; lo 147 vrshr.s16 q5, q5, #3 148 vrshr.s16 q6, q6, #3 ; hi 149 vrshr.s16 q7, q7, #3 150 151 vtrn.32 q4, q6 152 vtrn.32 q5, q7 153 vtrn.16 q4, q5 154 vtrn.16 q6, q7 155 156 ; adding pre 157 ; input is still packed. pre was read interleaved 158 vaddw.u8 q4, q4, d28 159 vaddw.u8 q5, q5, d29 160 vaddw.u8 q6, q6, d30 161 vaddw.u8 q7, q7, d31 162 163 vmov.i16 q14, #0 164 vmov q15, q14 165 vst1.16 {q14, q15}, [r0] ; write over high input 166 sub r0, r0, #32 167 vst1.16 {q14, q15}, [r0] ; write over low input 168 169 sub r2, r2, r3, lsl #2 ; dst - 4*stride 170 add r1, r2, #4 ; hi 171 172 ;saturate and narrow 173 vqmovun.s16 d0, q4 ; lo 174 vqmovun.s16 d1, q5 175 vqmovun.s16 d2, q6 ; hi 176 vqmovun.s16 d3, q7 177 178 vst1.32 {d0[0]}, [r2], r3 ; lo 179 vst1.32 {d0[1]}, [r1], r3 ; hi 180 vst1.32 {d1[0]}, [r2], r3 181 vst1.32 {d1[1]}, [r1], r3 182 vst1.32 {d2[0]}, [r2], r3 183 vst1.32 {d2[1]}, [r1], r3 184 vst1.32 {d3[0]}, [r2] 185 vst1.32 {d3[1]}, [r1] 186 187 bx lr 188 189 ENDP ; |idct_dequant_full_2x_neon| 190 191 ; Constant Pool 192 cospi8sqrt2minus1 DCD 0x4e7b 193 ; because the lowest bit in 0x8a8c is 0, we can pre-shift this 194 sinpi8sqrt2 DCD 0x4546 195 196 END 197
