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43 lines
1.2 KiB
ArmAsm
43 lines
1.2 KiB
ArmAsm
;
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; 1998-06-02, Ullrich von Bassewitz
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; 2013-08-28, Greg King
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;
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; char* __fastcall__ strlower (char* s);
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; char* __fastcall__ strlwr (char* s);
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;
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; Non-ANSI
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;
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.export _strlower, _strlwr
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.import popax
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.importzp ptr1, ptr2
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.import ctypemaskdirect
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.include "ctype.inc"
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_strlower:
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_strlwr:
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sta ptr1 ; save s (working copy)
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stx ptr1+1
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sta ptr2
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stx ptr2+1 ; save function result
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ldy #0
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loop: lda (ptr1),y ; get character
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beq L9 ; jump if done
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jsr ctypemaskdirect ; get character classification
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and #CT_UPPER ; upper case char?
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beq L1 ; jump if no
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lda (ptr1),y ; fetch character again
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adc #<('a'-'A') ; make lower case char (ctypemaskdirect ensures carry clear)
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sta (ptr1),y ; store back
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L1: iny ; next char
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bne loop
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inc ptr1+1 ; handle offset overflow
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bne loop ; branch always
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; Done, return the argument string
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L9: lda ptr2
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ldx ptr2+1
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rts
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