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103 lines
2.3 KiB
ArmAsm
103 lines
2.3 KiB
ArmAsm
;
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; Mark Keates, Christian Groessler, Piotr Fusik, Karri Kaksonen
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;
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; void cputcxy (unsigned char x, unsigned char y, char c);
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; void cputc (char c);
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;
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.export _mono_cputc
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.import mono_gotox, mono_gotoy, pusha0
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.import pushax
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.import _mono_screen
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.include "atari7800.inc"
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.include "extzp.inc"
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.code
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;---------------------------------------------------------------------------
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; 8x16 routine
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umula0:
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ldy #8 ; Number of bits
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lda #0
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lsr ptr7800 ; Get first bit into carry
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@L0: bcc @L1
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clc
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adc ptrtmp
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tax
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lda ptrtmp+1 ; hi byte of left op
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clc
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adc ptr7800+1
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sta ptr7800+1
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txa
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@L1: ror ptr7800+1
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ror a
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ror ptr7800
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dey
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bne @L0
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tax
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lda ptr7800 ; Load the result
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rts
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;-----------------------------------------------------------------------------
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; Put a character on screen
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;
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; The code will handle newlines that wrap to start of screen
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;
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.proc _mono_cputc
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cmp #$0A ; LF
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bne @L4
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@L1: lda #0 ; newline
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jsr mono_gotox
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lda CURS_Y
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cmp #(screenrows-1)
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bne @L2
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lda #0
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beq @L3
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@L2: clc
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adc #1
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@L3: jmp mono_gotoy
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@L4:
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pha
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lda #0
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sta ptr7800+1
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sta ptrtmp+1
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lda CURS_Y ; Find position on screen buffer
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sta ptr7800
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lda #mono_charsperline
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sta ptrtmp
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jsr umula0
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clc
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adc CURS_X
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bcc @L11
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inx
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@L11: clc
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adc #<(_mono_screen)
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sta ptr7800
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bcc @L12
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inx
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@L12: txa
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clc
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adc #>(_mono_screen)
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sta ptr7800+1
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pla ; Print character on screen
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ldy #0
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sta (ptr7800),y
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lda CURS_X ; Increment cursor
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cmp #(mono_charsperline-1)
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beq @L1
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clc
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adc #1
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jmp mono_gotox
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.endproc
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