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147 lines
2.0 KiB
ArmAsm
147 lines
2.0 KiB
ArmAsm
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; Ullrich von Bassewitz, 31.05.1998
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;
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; char* itoa (int value, char* s, int radix);
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; char* utoa (unsigned value, char* s, int radix);
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;
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.export _itoa, _utoa
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.import addysp1
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.import __hextab
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.importzp sp, sreg, ptr2, ptr3, tmp1
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.rodata
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specval:
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.byte '-', '3', '2', '7', '6', '8', 0
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.code
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;
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; Common subroutine to pop the parameters and put them into core
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;
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dopop: sta tmp1 ; will loose high byte
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ldy #0
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lda (sp),y
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sta ptr2
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sta ptr3
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iny
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lda (sp),y
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sta ptr2+1
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sta ptr3+1
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iny
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lda (sp),y
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sta sreg
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iny
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lda (sp),y
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sta sreg+1
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jmp addysp1 ; Bump stack pointer
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;
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; itoa
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;
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_itoa: jsr dopop ; pop the arguments
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; We must handle $8000 in a special way, since it is the only negative
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; number that has no positive 16-bit counterpart
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ldy tmp1 ; get radix
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cpy #10
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bne utoa
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cmp #$00
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bne L2
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cpx #$80
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bne L2
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ldy #6
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L1: lda specval,y ; copy -32768
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sta (ptr2),y
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dey
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bpl L1
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jmp L10
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; Check if the value is negative. If so, write a - sign and negate the
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; number.
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L2: lda sreg+1 ; get high byte
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bpl utoa
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lda #'-'
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ldy #0
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sta (ptr2),y ; store sign
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inc ptr2
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bne L3
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inc ptr2+1
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L3: lda sreg
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eor #$FF
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clc
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adc #$01
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sta sreg
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lda sreg+1
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eor #$FF
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adc #$00
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sta sreg+1
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jmp utoa
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;
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; utoa
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;
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_utoa: jsr dopop ; pop the arguments
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; Convert to string by dividing and push the result onto the stack
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utoa: lda #$00
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pha ; sentinel
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; Divide sreg/tmp1 -> sreg, remainder in a
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L5: ldy #16 ; 16 bit
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lda #0 ; remainder
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L6: asl sreg
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rol sreg+1
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rol a
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cmp tmp1
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bcc L7
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sbc tmp1
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inc sreg
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L7: dey
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bne L6
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tay ; get remainder into y
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lda __hextab,y ; get hex character
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pha ; save char value on stack
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lda sreg
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ora sreg+1
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bne L5
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; Get the characters from the stack into the string
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ldy #0
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L9: pla
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sta (ptr2),y
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beq L10 ; jump if sentinel
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iny
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bne L9 ; jump always
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; Done! Return the target string
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L10: lda ptr3
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ldx ptr3+1
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rts
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