1/* libs/pixelflinger/col32cb16blend_neon.S 2 * 3 * Copyright (C) 2009 The Android Open Source Project 4 * 5 * Licensed under the Apache License, Version 2.0 (the "License"); 6 * you may not use this file except in compliance with the License. 7 * You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 18 19 .text 20 .align 21 22 .global scanline_col32cb16blend_neon 23 24// 25// This function alpha blends a fixed color into a destination scanline, using 26// the formula: 27// 28// d = s + (((a + (a >> 7)) * d) >> 8) 29// 30// where d is the destination pixel, 31// s is the source color, 32// a is the alpha channel of the source color. 33// 34// The NEON implementation processes 16 pixels per iteration. The remaining 0 - 15 35// pixels are processed in ARM code. 36// 37 38// r0 = destination buffer pointer 39// r1 = color pointer 40// r2 = count 41 42 43scanline_col32cb16blend_neon: 44 push {r4-r11, lr} // stack ARM regs 45 46 vmov.u16 q15, #256 // create alpha constant 47 movs r3, r2, lsr #4 // calc. sixteens iterations 48 vmov.u16 q14, #0x1f // create blue mask 49 50 beq 2f // if r3 == 0, branch to singles 51 52 vld4.8 {d0[], d2[], d4[], d6[]}, [r1] // load color into four registers 53 // split and duplicate them, such that 54 // d0 = 8 equal red values 55 // d2 = 8 equal green values 56 // d4 = 8 equal blue values 57 // d6 = 8 equal alpha values 58 vshll.u8 q0, d0, #5 // shift up red and widen 59 vshll.u8 q1, d2, #6 // shift up green and widen 60 vshll.u8 q2, d4, #5 // shift up blue and widen 61 62 vshr.u8 d7, d6, #7 // extract top bit of alpha 63 vaddl.u8 q3, d6, d7 // add top bit into alpha 64 vsub.u16 q3, q15, q3 // invert alpha 65 661: 67 // This loop processes 16 pixels per iteration. In the comments, references to 68 // the first eight pixels are suffixed with "0" (red0, green0, blue0), 69 // the second eight are suffixed "1". 70 // q8 = dst red0 71 // q9 = dst green0 72 // q10 = dst blue0 73 // q13 = dst red1 74 // q12 = dst green1 75 // q11 = dst blue1 76 77 vld1.16 {d20, d21, d22, d23}, [r0] // load 16 dest pixels 78 vshr.u16 q8, q10, #11 // shift dst red0 to low 5 bits 79 pld [r0, #63] // preload next dest pixels 80 vshl.u16 q9, q10, #5 // shift dst green0 to top 6 bits 81 vand q10, q10, q14 // extract dst blue0 82 vshr.u16 q9, q9, #10 // shift dst green0 to low 6 bits 83 vmul.u16 q8, q8, q3 // multiply dst red0 by src alpha 84 vshl.u16 q12, q11, #5 // shift dst green1 to top 6 bits 85 vmul.u16 q9, q9, q3 // multiply dst green0 by src alpha 86 vshr.u16 q13, q11, #11 // shift dst red1 to low 5 bits 87 vmul.u16 q10, q10, q3 // multiply dst blue0 by src alpha 88 vshr.u16 q12, q12, #10 // shift dst green1 to low 6 bits 89 vand q11, q11, q14 // extract dst blue1 90 vadd.u16 q8, q8, q0 // add src red to dst red0 91 vmul.u16 q13, q13, q3 // multiply dst red1 by src alpha 92 vadd.u16 q9, q9, q1 // add src green to dst green0 93 vmul.u16 q12, q12, q3 // multiply dst green1 by src alpha 94 vadd.u16 q10, q10, q2 // add src blue to dst blue0 95 vmul.u16 q11, q11, q3 // multiply dst blue1 by src alpha 96 vshr.u16 q8, q8, #8 // shift down red0 97 vadd.u16 q13, q13, q0 // add src red to dst red1 98 vshr.u16 q9, q9, #8 // shift down green0 99 vadd.u16 q12, q12, q1 // add src green to dst green1 100 vshr.u16 q10, q10, #8 // shift down blue0 101 vadd.u16 q11, q11, q2 // add src blue to dst blue1 102 vsli.u16 q10, q9, #5 // shift & insert green0 into blue0 103 vshr.u16 q13, q13, #8 // shift down red1 104 vsli.u16 q10, q8, #11 // shift & insert red0 into blue0 105 vshr.u16 q12, q12, #8 // shift down green1 106 vshr.u16 q11, q11, #8 // shift down blue1 107 subs r3, r3, #1 // decrement loop counter 108 vsli.u16 q11, q12, #5 // shift & insert green1 into blue1 109 vsli.u16 q11, q13, #11 // shift & insert red1 into blue1 110 111 vst1.16 {d20, d21, d22, d23}, [r0]! // write 16 pixels back to dst 112 bne 1b // if count != 0, loop 113 1142: 115 ands r3, r2, #15 // calc. single iterations 116 beq 4f // if r3 == 0, exit 117 118 ldr r4, [r1] // load source color 119 mov r5, r4, lsr #24 // shift down alpha 120 add r5, r5, r5, lsr #7 // add in top bit 121 rsb r5, r5, #256 // invert alpha 122 and r11, r4, #0xff // extract red 123 ubfx r12, r4, #8, #8 // extract green 124 ubfx r4, r4, #16, #8 // extract blue 125 mov r11, r11, lsl #5 // prescale red 126 mov r12, r12, lsl #6 // prescale green 127 mov r4, r4, lsl #5 // prescale blue 128 1293: 130 ldrh r8, [r0] // load dest pixel 131 subs r3, r3, #1 // decrement loop counter 132 mov r6, r8, lsr #11 // extract dest red 133 ubfx r7, r8, #5, #6 // extract dest green 134 and r8, r8, #0x1f // extract dest blue 135 136 smlabb r6, r6, r5, r11 // dest red * alpha + src red 137 smlabb r7, r7, r5, r12 // dest green * alpha + src green 138 smlabb r8, r8, r5, r4 // dest blue * alpha + src blue 139 140 mov r6, r6, lsr #8 // shift down red 141 mov r7, r7, lsr #8 // shift down green 142 mov r6, r6, lsl #11 // shift red into 565 143 orr r6, r7, lsl #5 // shift green into 565 144 orr r6, r8, lsr #8 // shift blue into 565 145 146 strh r6, [r0], #2 // store pixel to dest, update ptr 147 bne 3b // if count != 0, loop 1484: 149 150 pop {r4-r11, pc} // return 151 152 153 154