1 /*************************************************************************** 2 Copyright (c) 2009,2010, Code Aurora Forum. All rights reserved. 3 4 Licensed under the Apache License, Version 2.0 (the "License"); you 5 may not use this file except in compliance with the License. You may 6 obtain a copy of the License at 7 8 http://www.apache.org/licenses/LICENSE-2.0 9 10 Unless required by applicable law or agreed to in writing, software 11 distributed under the License is distributed on an "AS IS" BASIS, 12 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or 13 implied. See the License for the specific language governing 14 permissions and limitations under the License. 15 ***************************************************************************/ 16 17 /*************************************************************************** 18 Neon memset: Attempts to do a memset with Neon registers if possible, 19 Inputs: 20 s: The buffer to write to 21 c: The integer data to write to the buffer 22 n: The size_t count. 23 Outputs: 24 25 ***************************************************************************/ 26 27 .code 32 28 .fpu neon 29 .align 4 30 .globl memset16_neon 31 .func 32 33 memset16_neon: 34 cmp r2, #0 35 bxeq lr 36 37 /* Keep in mind that r2 -- the count argument -- is for the 38 * number of 16-bit items to copy. 39 */ 40 lsl r2, r2, #1 41 42 push {r0} 43 44 /* If we have < 8 bytes, just do a quick loop to handle that */ 45 cmp r2, #8 46 bgt memset_gt4 47 memset_smallcopy_loop: 48 strh r1, [r0], #2 49 subs r2, r2, #2 50 bne memset_smallcopy_loop 51 memset_smallcopy_done: 52 pop {r0} 53 bx lr 54 55 memset_gt4: 56 /* 57 * Duplicate the r1 lowest 16-bits across r1. The idea is to have 58 * a register with two 16-bit-values we can copy. We do this by 59 * duplicating lowest 16-bits of r1 to upper 16-bits. 60 */ 61 orr r1, r1, r1, lsl #16 62 /* 63 * If we're copying > 64 bytes, then we may want to get 64 * onto a 16-byte boundary to improve speed even more. 65 */ 66 cmp r2, #64 67 blt memset_route 68 ands r12, r0, #0xf 69 beq memset_route 70 /* 71 * Determine the number of bytes to move forward to get to the 16-byte 72 * boundary. Note that this will be a multiple of 4, since we 73 * already are word-aligned. 74 */ 75 rsb r12, r12, #16 76 sub r2, r2, r12 77 lsls r12, r12, #29 78 strmi r1, [r0], #4 79 strcs r1, [r0], #4 80 strcs r1, [r0], #4 81 lsls r12, r12, #2 82 strcsh r1, [r0], #2 83 memset_route: 84 /* 85 * Decide where to route for the maximum copy sizes. Note that we 86 * build q0 and q1 depending on if we'll need it, so that's 87 * interwoven here as well. 88 */ 89 vdup.u32 d0, r1 90 cmp r2, #16 91 blt memset_8 92 vmov d1, d0 93 cmp r2, #64 94 blt memset_16 95 vmov q1, q0 96 cmp r2, #128 97 blt memset_32 98 memset_128: 99 mov r12, r2, lsr #7 100 memset_128_loop: 101 vst1.64 {q0, q1}, [r0]! 102 vst1.64 {q0, q1}, [r0]! 103 vst1.64 {q0, q1}, [r0]! 104 vst1.64 {q0, q1}, [r0]! 105 subs r12, r12, #1 106 bne memset_128_loop 107 ands r2, r2, #0x7f 108 beq memset_end 109 memset_32: 110 movs r12, r2, lsr #5 111 beq memset_16 112 memset_32_loop: 113 subs r12, r12, #1 114 vst1.64 {q0, q1}, [r0]! 115 bne memset_32_loop 116 ands r2, r2, #0x1f 117 beq memset_end 118 memset_16: 119 movs r12, r2, lsr #4 120 beq memset_8 121 memset_16_loop: 122 subs r12, r12, #1 123 vst1.32 {q0}, [r0]! 124 bne memset_16_loop 125 ands r2, r2, #0xf 126 beq memset_end 127 /* 128 * memset_8 isn't a loop, since we try to do our loops at 16 129 * bytes and above. We should loop there, then drop down here 130 * to finish the <16-byte versions. Same for memset_4 and 131 * memset_1. 132 */ 133 memset_8: 134 cmp r2, #8 135 blt memset_4 136 subs r2, r2, #8 137 vst1.32 {d0}, [r0]! 138 memset_4: 139 cmp r2, #4 140 blt memset_2 141 subs r2, r2, #4 142 str r1, [r0], #4 143 memset_2: 144 cmp r2, #0 145 ble memset_end 146 strh r1, [r0], #2 147 memset_end: 148 pop {r0} 149 bx lr 150 151 .endfunc 152 .end 153
