/* libs/pixelflinger/col32cb16blend_neon.S * * Copyright (C) 2009 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ .text .align .global scanline_col32cb16blend_neon // // This function alpha blends a fixed color into a destination scanline, using // the formula: // // d = s + (((a + (a >> 7)) * d) >> 8) // // where d is the destination pixel, // s is the source color, // a is the alpha channel of the source color. // // The NEON implementation processes 16 pixels per iteration. The remaining 0 - 15 // pixels are processed in ARM code. // // r0 = destination buffer pointer // r1 = color pointer // r2 = count scanline_col32cb16blend_neon: push {r4-r11, lr} // stack ARM regs vmov.u16 q15, #256 // create alpha constant movs r3, r2, lsr #4 // calc. sixteens iterations vmov.u16 q14, #0x1f // create blue mask beq 2f // if r3 == 0, branch to singles vld4.8 {d0[], d2[], d4[], d6[]}, [r1] // load color into four registers // split and duplicate them, such that // d0 = 8 equal red values // d2 = 8 equal green values // d4 = 8 equal blue values // d6 = 8 equal alpha values vshll.u8 q0, d0, #5 // shift up red and widen vshll.u8 q1, d2, #6 // shift up green and widen vshll.u8 q2, d4, #5 // shift up blue and widen vshr.u8 d7, d6, #7 // extract top bit of alpha vaddl.u8 q3, d6, d7 // add top bit into alpha vsub.u16 q3, q15, q3 // invert alpha 1: // This loop processes 16 pixels per iteration. In the comments, references to // the first eight pixels are suffixed with "0" (red0, green0, blue0), // the second eight are suffixed "1". // q8 = dst red0 // q9 = dst green0 // q10 = dst blue0 // q13 = dst red1 // q12 = dst green1 // q11 = dst blue1 vld1.16 {d20, d21, d22, d23}, [r0] // load 16 dest pixels vshr.u16 q8, q10, #11 // shift dst red0 to low 5 bits pld [r0, #63] // preload next dest pixels vshl.u16 q9, q10, #5 // shift dst green0 to top 6 bits vand q10, q10, q14 // extract dst blue0 vshr.u16 q9, q9, #10 // shift dst green0 to low 6 bits vmul.u16 q8, q8, q3 // multiply dst red0 by src alpha vshl.u16 q12, q11, #5 // shift dst green1 to top 6 bits vmul.u16 q9, q9, q3 // multiply dst green0 by src alpha vshr.u16 q13, q11, #11 // shift dst red1 to low 5 bits vmul.u16 q10, q10, q3 // multiply dst blue0 by src alpha vshr.u16 q12, q12, #10 // shift dst green1 to low 6 bits vand q11, q11, q14 // extract dst blue1 vadd.u16 q8, q8, q0 // add src red to dst red0 vmul.u16 q13, q13, q3 // multiply dst red1 by src alpha vadd.u16 q9, q9, q1 // add src green to dst green0 vmul.u16 q12, q12, q3 // multiply dst green1 by src alpha vadd.u16 q10, q10, q2 // add src blue to dst blue0 vmul.u16 q11, q11, q3 // multiply dst blue1 by src alpha vshr.u16 q8, q8, #8 // shift down red0 vadd.u16 q13, q13, q0 // add src red to dst red1 vshr.u16 q9, q9, #8 // shift down green0 vadd.u16 q12, q12, q1 // add src green to dst green1 vshr.u16 q10, q10, #8 // shift down blue0 vadd.u16 q11, q11, q2 // add src blue to dst blue1 vsli.u16 q10, q9, #5 // shift & insert green0 into blue0 vshr.u16 q13, q13, #8 // shift down red1 vsli.u16 q10, q8, #11 // shift & insert red0 into blue0 vshr.u16 q12, q12, #8 // shift down green1 vshr.u16 q11, q11, #8 // shift down blue1 subs r3, r3, #1 // decrement loop counter vsli.u16 q11, q12, #5 // shift & insert green1 into blue1 vsli.u16 q11, q13, #11 // shift & insert red1 into blue1 vst1.16 {d20, d21, d22, d23}, [r0]! // write 16 pixels back to dst bne 1b // if count != 0, loop 2: ands r3, r2, #15 // calc. single iterations beq 4f // if r3 == 0, exit ldr r4, [r1] // load source color mov r5, r4, lsr #24 // shift down alpha add r5, r5, r5, lsr #7 // add in top bit rsb r5, r5, #256 // invert alpha and r11, r4, #0xff // extract red ubfx r12, r4, #8, #8 // extract green ubfx r4, r4, #16, #8 // extract blue mov r11, r11, lsl #5 // prescale red mov r12, r12, lsl #6 // prescale green mov r4, r4, lsl #5 // prescale blue 3: ldrh r8, [r0] // load dest pixel subs r3, r3, #1 // decrement loop counter mov r6, r8, lsr #11 // extract dest red ubfx r7, r8, #5, #6 // extract dest green and r8, r8, #0x1f // extract dest blue smlabb r6, r6, r5, r11 // dest red * alpha + src red smlabb r7, r7, r5, r12 // dest green * alpha + src green smlabb r8, r8, r5, r4 // dest blue * alpha + src blue mov r6, r6, lsr #8 // shift down red mov r7, r7, lsr #8 // shift down green mov r6, r6, lsl #11 // shift red into 565 orr r6, r7, lsl #5 // shift green into 565 orr r6, r8, lsr #8 // shift blue into 565 strh r6, [r0], #2 // store pixel to dest, update ptr bne 3b // if count != 0, loop 4: pop {r4-r11, pc} // return