| 1,5 → 1,5 |
|---|
| # |
| # Copyright (c) 2006 Martin Decky |
| # Copyright (c) 2007 Michal Kebrt |
| # All rights reserved. |
| # |
| # Redistribution and use in source and binary forms, with or without |
| 29,147 → 29,58 |
|---|
| |
| .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 |
| |
| .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 |
| add r3, r1, #3 |
| bic r3, r3, #3 |
| cmp r1, r3 |
| stmdb sp!, {r4, lr} |
| beq case_4 |
| case_1: |
| cmp r2, #0 |
| movne ip, #0 |
| beq case_3 |
| case_2: |
| ldrb r3, [ip, r1] |
| strb r3, [ip, r0] |
| add ip, ip, #1 |
| cmp ip, r2 |
| bne case_2 |
| case_3: |
| mov r0, r1 |
| ldmia sp!, {r4, pc} |
| case_4: |
| add r3, r0, #3 |
| bic r3, r3, #3 |
| cmp r0, r3 |
| bne case_1 |
| movs r4, r2, lsr #2 |
| moveq lr, r4 |
| beq case_6 |
| mov lr, #0 |
| mov ip, lr |
| case_5: |
| ldr r3, [ip, r1] |
| add lr, lr, #1 |
| cmp lr, r4 |
| str r3, [ip, r0] |
| add ip, ip, #4 |
| bne case_5 |
| case_6: |
| ands r4, r2, #3 |
| beq case_3 |
| mov r3, lr, lsl #2 |
| add r0, r3, r0 |
| add ip, r3, r1 |
| mov r2, #0 |
| case_7: |
| ldrb r3, [r2, ip] |
| strb r3, [r2, r0] |
| add r2, r2, #1 |
| cmp r2, r4 |
| bne case_7 |
| b case_3 |
| |
| 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: |
| |