/* * Copyright (C) 2008 The Android Open Source Project * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ .text .global memcpy .type memcpy, %function .align 4 /* * Optimized memcpy() for ARM. * * note that memcpy() always returns the destination pointer, * so we have to preserve R0. */ memcpy: /* The stack must always be 64-bits aligned to be compliant with the * ARM ABI. Since we have to save R0, we might as well save R4 * which we can use for better pipelining of the reads below */ .fnstart .save {r0, r4, lr} stmfd sp!, {r0, r4, lr} /* Making room for r5-r11 which will be spilled later */ .pad #28 sub sp, sp, #28 // preload the destination because we'll align it to a cache line // with small writes. Also start the source "pump". pld [r0, #0] pld [r1, #0] pld [r1, #32] /* it simplifies things to take care of len<4 early */ cmp r2, #4 blo copy_last_3_and_return /* compute the offset to align the source * offset = (4-(src&3))&3 = -src & 3 */ rsb r3, r1, #0 ands r3, r3, #3 beq src_aligned /* align source to 32 bits. We need to insert 2 instructions between * a ldr[b|h] and str[b|h] because byte and half-word instructions * stall 2 cycles. */ movs r12, r3, lsl #31 sub r2, r2, r3 /* we know that r3 <= r2 because r2 >= 4 */ ldrmib r3, [r1], #1 ldrcsb r4, [r1], #1 ldrcsb r12,[r1], #1 strmib r3, [r0], #1 strcsb r4, [r0], #1 strcsb r12,[r0], #1 src_aligned: /* see if src and dst are aligned together (congruent) */ eor r12, r0, r1 tst r12, #3 bne non_congruent /* Use post-incriment mode for stm to spill r5-r11 to reserved stack * frame. Don't update sp. */ stmea sp, {r5-r11} /* align the destination to a cache-line */ rsb r3, r0, #0 ands r3, r3, #0x1C beq congruent_aligned32 cmp r3, r2 andhi r3, r2, #0x1C /* conditionnaly copies 0 to 7 words (length in r3) */ movs r12, r3, lsl #28 ldmcsia r1!, {r4, r5, r6, r7} /* 16 bytes */ ldmmiia r1!, {r8, r9} /* 8 bytes */ stmcsia r0!, {r4, r5, r6, r7} stmmiia r0!, {r8, r9} tst r3, #0x4 ldrne r10,[r1], #4 /* 4 bytes */ strne r10,[r0], #4 sub r2, r2, r3 congruent_aligned32: /* * here source is aligned to 32 bytes. */ cached_aligned32: subs r2, r2, #32 blo less_than_32_left /* * We preload a cache-line up to 64 bytes ahead. On the 926, this will * stall only until the requested world is fetched, but the linefill * continues in the the background. * While the linefill is going, we write our previous cache-line * into the write-buffer (which should have some free space). * When the linefill is done, the writebuffer will * start dumping its content into memory * * While all this is going, we then load a full cache line into * 8 registers, this cache line should be in the cache by now * (or partly in the cache). * * This code should work well regardless of the source/dest alignment. * */ // Align the preload register to a cache-line because the cpu does // "critical word first" (the first word requested is loaded first). bic r12, r1, #0x1F add r12, r12, #64 1: ldmia r1!, { r4-r11 } pld [r12, #64] subs r2, r2, #32 // NOTE: if r12 is more than 64 ahead of r1, the following ldrhi // for ARM9 preload will not be safely guarded by the preceding subs. // When it is safely guarded the only possibility to have SIGSEGV here // is because the caller overstates the length. ldrhi r3, [r12], #32 /* cheap ARM9 preload */ stmia r0!, { r4-r11 } bhs 1b add r2, r2, #32 less_than_32_left: /* * less than 32 bytes left at this point (length in r2) */ /* skip all this if there is nothing to do, which should * be a common case (if not executed the code below takes * about 16 cycles) */ tst r2, #0x1F beq 1f /* conditionnaly copies 0 to 31 bytes */ movs r12, r2, lsl #28 ldmcsia r1!, {r4, r5, r6, r7} /* 16 bytes */ ldmmiia r1!, {r8, r9} /* 8 bytes */ stmcsia r0!, {r4, r5, r6, r7} stmmiia r0!, {r8, r9} movs r12, r2, lsl #30 ldrcs r3, [r1], #4 /* 4 bytes */ ldrmih r4, [r1], #2 /* 2 bytes */ strcs r3, [r0], #4 strmih r4, [r0], #2 tst r2, #0x1 ldrneb r3, [r1] /* last byte */ strneb r3, [r0] /* we're done! restore everything and return */ 1: ldmfd sp!, {r5-r11} ldmfd sp!, {r0, r4, lr} bx lr /********************************************************************/ non_congruent: /* * here source is aligned to 4 bytes * but destination is not. * * in the code below r2 is the number of bytes read * (the number of bytes written is always smaller, because we have * partial words in the shift queue) */ cmp r2, #4 blo copy_last_3_and_return /* Use post-incriment mode for stm to spill r5-r11 to reserved stack * frame. Don't update sp. */ stmea sp, {r5-r11} /* compute shifts needed to align src to dest */ rsb r5, r0, #0 and r5, r5, #3 /* r5 = # bytes in partial words */ mov r12, r5, lsl #3 /* r12 = right */ rsb lr, r12, #32 /* lr = left */ /* read the first word */ ldr r3, [r1], #4 sub r2, r2, #4 /* write a partial word (0 to 3 bytes), such that destination * becomes aligned to 32 bits (r5 = nb of words to copy for alignment) */ movs r5, r5, lsl #31 strmib r3, [r0], #1 movmi r3, r3, lsr #8 strcsb r3, [r0], #1 movcs r3, r3, lsr #8 strcsb r3, [r0], #1 movcs r3, r3, lsr #8 cmp r2, #4 blo partial_word_tail /* Align destination to 32 bytes (cache line boundary) */ 1: tst r0, #0x1c beq 2f ldr r5, [r1], #4 sub r2, r2, #4 orr r4, r3, r5, lsl lr mov r3, r5, lsr r12 str r4, [r0], #4 cmp r2, #4 bhs 1b blo partial_word_tail /* copy 32 bytes at a time */ 2: subs r2, r2, #32 blo less_than_thirtytwo /* Use immediate mode for the shifts, because there is an extra cycle * for register shifts, which could account for up to 50% of * performance hit. */ cmp r12, #24 beq loop24 cmp r12, #8 beq loop8 loop16: ldr r12, [r1], #4 1: mov r4, r12 ldmia r1!, { r5,r6,r7, r8,r9,r10,r11} pld [r1, #64] subs r2, r2, #32 ldrhs r12, [r1], #4 orr r3, r3, r4, lsl #16 mov r4, r4, lsr #16 orr r4, r4, r5, lsl #16 mov r5, r5, lsr #16 orr r5, r5, r6, lsl #16 mov r6, r6, lsr #16 orr r6, r6, r7, lsl #16 mov r7, r7, lsr #16 orr r7, r7, r8, lsl #16 mov r8, r8, lsr #16 orr r8, r8, r9, lsl #16 mov r9, r9, lsr #16 orr r9, r9, r10, lsl #16 mov r10, r10, lsr #16 orr r10, r10, r11, lsl #16 stmia r0!, {r3,r4,r5,r6, r7,r8,r9,r10} mov r3, r11, lsr #16 bhs 1b b less_than_thirtytwo loop8: ldr r12, [r1], #4 1: mov r4, r12 ldmia r1!, { r5,r6,r7, r8,r9,r10,r11} pld [r1, #64] subs r2, r2, #32 ldrhs r12, [r1], #4 orr r3, r3, r4, lsl #24 mov r4, r4, lsr #8 orr r4, r4, r5, lsl #24 mov r5, r5, lsr #8 orr r5, r5, r6, lsl #24 mov r6, r6, lsr #8 orr r6, r6, r7, lsl #24 mov r7, r7, lsr #8 orr r7, r7, r8, lsl #24 mov r8, r8, lsr #8 orr r8, r8, r9, lsl #24 mov r9, r9, lsr #8 orr r9, r9, r10, lsl #24 mov r10, r10, lsr #8 orr r10, r10, r11, lsl #24 stmia r0!, {r3,r4,r5,r6, r7,r8,r9,r10} mov r3, r11, lsr #8 bhs 1b b less_than_thirtytwo loop24: ldr r12, [r1], #4 1: mov r4, r12 ldmia r1!, { r5,r6,r7, r8,r9,r10,r11} pld [r1, #64] subs r2, r2, #32 ldrhs r12, [r1], #4 orr r3, r3, r4, lsl #8 mov r4, r4, lsr #24 orr r4, r4, r5, lsl #8 mov r5, r5, lsr #24 orr r5, r5, r6, lsl #8 mov r6, r6, lsr #24 orr r6, r6, r7, lsl #8 mov r7, r7, lsr #24 orr r7, r7, r8, lsl #8 mov r8, r8, lsr #24 orr r8, r8, r9, lsl #8 mov r9, r9, lsr #24 orr r9, r9, r10, lsl #8 mov r10, r10, lsr #24 orr r10, r10, r11, lsl #8 stmia r0!, {r3,r4,r5,r6, r7,r8,r9,r10} mov r3, r11, lsr #24 bhs 1b less_than_thirtytwo: /* copy the last 0 to 31 bytes of the source */ rsb r12, lr, #32 /* we corrupted r12, recompute it */ add r2, r2, #32 cmp r2, #4 blo partial_word_tail 1: ldr r5, [r1], #4 sub r2, r2, #4 orr r4, r3, r5, lsl lr mov r3, r5, lsr r12 str r4, [r0], #4 cmp r2, #4 bhs 1b partial_word_tail: /* we have a partial word in the input buffer */ movs r5, lr, lsl #(31-3) strmib r3, [r0], #1 movmi r3, r3, lsr #8 strcsb r3, [r0], #1 movcs r3, r3, lsr #8 strcsb r3, [r0], #1 /* Refill spilled registers from the stack. Don't update sp. */ ldmfd sp, {r5-r11} copy_last_3_and_return: movs r2, r2, lsl #31 /* copy remaining 0, 1, 2 or 3 bytes */ ldrmib r2, [r1], #1 ldrcsb r3, [r1], #1 ldrcsb r12,[r1] strmib r2, [r0], #1 strcsb r3, [r0], #1 strcsb r12,[r0] /* we're done! restore sp and spilled registers and return */ add sp, sp, #28 ldmfd sp!, {r0, r4, lr} bx lr .fnend