50 lines
666 B
ArmAsm
50 lines
666 B
ArmAsm
.text
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.syntax unified
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.global memcpy
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.func memcpy
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.thumb_func
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memcpy:
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/* on entry
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* r0 = targ
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* r1 = src
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* r2 = len (bytes)
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* on exit
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* r0 = targ (unchanged)
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*/
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push {r0, r4, lr}
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/* If targ or src are unaligned, drop to byte
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* processing. */
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mov r3, r0
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movs r4, #3
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orrs r3, r1
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ands r3, r4
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bne L_bytewise
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/* Process words */
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L_wordwise:
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cmp r2, #4
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blo L_bytewise
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ldr r4, [r1]
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adds r1, #4
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str r4, [r0]
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adds r0, #4
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subs r2, #4
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b L_wordwise
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/* Process bytes */
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L_bytewise:
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cmp r2, #0
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beq L_fin
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ldrb r4, [r1]
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adds r1, #1
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strb r4, [r0]
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adds r0, #1
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subs r2, #1
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b L_bytewise
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L_fin:
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pop {r0, r4, pc}
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.endfunc
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