| 0,0 → 1,175 |
|---|
| # |
| # Copyright (c) 2006 Martin Decky |
| # 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. |
| # - The name of the author may not be used to endorse or promote products |
| # derived from this software without specific prior written permission. |
| # |
| # THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 |
| |
| .align 2 |
| |
| |
| different_aligns: |
| /* We must do byte copies */ |
| stmfd r13!, {r0, lr } |
| byte_loop: |
| ldrb r3, [r1], #1 |
| strb r3, [r0], #1 |
| subs r2, r2, #1 |
| bne byte_loop |
| ldmfd r13!, {r0, pc } |
| |
| .global memcpy |
| .type memcpy, %function |
| memcpy: |
| @void* memcpy( void* dst, const void* src, size_t len ) |
| |
| @@ Register usage: |
| @@ r0: dst |
| @@ r1: src |
| @@ r2: len |
| @@ |
| @@ r3: various bitmasks, load and store for different_aligns loop |
| @@ r4: counter for multi loop, not used for different_aligns |
| @@ r5-r8: load and store, not used for different_aligns |
| |
| cmp r2, #0 |
| moveq pc, lr @ just return if caller wants to copy zero bytes |
| |
| cmp r2, #8 |
| bls different_aligns |
| |
| /*check for src alignment*/ |
| eor r3, r0, r1 @ r3 = dest | src |
| tst r3, #3 @ test for same alignment |
| bne different_aligns @ jump if align( r1 ) != align( ro ) |
| |
| /* else, they have the same same alignment */ |
| stmfd r13!, {r0, r4-r8, lr } @ save regs |
| ands r3, r0, #3 @ find out what that alignment is |
| beq multi @ iff align( r1 ) == align( r0 ) == 0 skip to multi |
| |
| /* otherwise, move up to three bytes to get to a word alignment |
| if align = 1, we need to move forward 3 bytes to get to a word boundry |
| if align = 2, we need to move forward 2 bytes to get to a word boundry |
| if align = 3, we need to move forward 1 byte to get to a word boundry |
| */ |
| cmp r3, #2 @ "subtract" 2 from either 1, 2, or 3 |
| ldrneb r4, [r1], #1 @ one aligned or three aligned ( 1 != 2 || 3 !- 2 ), ((byte*) src)++ |
| strneb r4, [r0], #1 @ one aligned or three aligned ( 1 != 2 || 3 !- 2 ), store to *dst++ |
| @ldrlsh r4, [r1], #2 @ one or two ( 1 <= 2 || 2 <= 2 ) aligned, ((halfword*) src)++ |
| @strlsh r4, [r0], #2 @ one or two ( 1 <= 2 || 2 <= 2 ) aligned, store to *dst++ |
| |
| ldrlsb r4, [r1], #1 @ one aligned or two aligned, ((byte*) src)++ |
| strlsb r4, [r0], #1 @ one aligned or two aligned, store to *dst++ |
| ldrlsb r4, [r1], #1 @ one aligned or two aligned, ((byte*) src)++ |
| strlsb r4, [r0], #1 @ one aligned or two aligned, store to *dst++ |
| |
| sub r3, r3, #4 |
| add r2, r2, r3 @ length -= bytes written |
| |
| multi: |
| /* once we get here, we're word aligned */ |
| |
| /* |
| bytes = length |
| words = byte / 4, rem = byte moves |
| instr = quadword = words / 4, rem = partial instructions |
| loop = instr / 4, rem = jump to instr |
| |
| 010101010 |
| llliiwwbb |
| |
| 21 |
| 52631 |
| 684268421 |
| */ |
| |
| ands r3, r2, #48 @ #32 | #16, r3 = partial loop count << 3 |
| mov r4, r2, LSR #6 @ r4 = loop count |
| |
| /* Now, like Duff's device, jump into the loop to perform the extra instructions */ |
| /* Replace later with direct adjustment of PC */ |
| beq loop_test |
| cmp r3, #32 @r3 = 16 or 32 or 48, corresponding to 1 or 2 or 3 |
| bhi loop3 |
| beq loop2 |
| blo loop1 |
| |
| loop: |
| ldmia r1!, { r5-r8 } @load four registers |
| stmia r0!, { r5-r8 } @store four registers |
| loop3: |
| ldmia r1!, { r5-r8 } @load four registers |
| stmia r0!, { r5-r8 } @store four registers |
| loop2: |
| ldmia r1!, { r5-r8 } @load four registers |
| stmia r0!, { r5-r8 } @store four registers |
| loop1: |
| ldmia r1!, { r5-r8 } @load four registers |
| stmia r0!, { r5-r8 } @store four registers |
| |
| loop_test: |
| cmp r4, #0 |
| subne r4, r4, #1 |
| bne loop |
| |
| /* Now do the extra words */ |
| ands r3, r2, #12 @ #8 | #4, r3 = extra words << 2 |
| beq extra_bytes |
| cmp r3, #8 |
| ldrne r5, [r1], #4 @ if r5 !=8 then it's 4 or 12, so load and store |
| strne r5, [r0], #4 |
| ldmhsia r1!, {r5-r6} @ if r5 >= 8, it's 8 or 12, so load and store 2 |
| stmhsia r0!, {r5-r6} |
| |
| /* Now do the extra bytes */ |
| extra_bytes: |
| tst r2, #2 @ any extra bytes? |
| beq clean_up |
| cmp r3, #2 @ subtract 2 from either 1, 2, or 3 |
| ldrneb r5, [r1], #1 @ load and store one byte iff r3 != 2 (i.e, r3 == 1 || r3 == 3) |
| strneb r5, [r0], #1 @ 1 or 3 |
| ldrhsb r5, [r1], #1 @ load and store a byte iff r3 >= 2 |
| strhsb r5, [r0], #1 @ 2 or 3 |
| ldrhsb r5, [r1], #1 @ load and store a byte iff r3 > 2 |
| strhsb r5, [r0], #1 @ 2 or 3 |
| |
| clean_up: |
| ldmfd r13!, {r0, r4-r8, pc } @r0 is the retval, must equal original dst |
| |
| end: |
| .size different_aligns, .end-memcpy |
| .align 2 |
| |
| @ Local Variables: |
| @ asm-comment-char: ?@ |
| @ comment-start: "@ " |
| @ block-comment-start: "/*" |
| @ block-comment-end: "*/" |
| @ indent-tabs-mode: t |
| @ End: |
| |