mirror of https://github.com/stid/woz64.git
40 lines
1.6 KiB
NASM
40 lines
1.6 KiB
NASM
#importonce
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#import "mem_map.asm"
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.filenamespace Hex
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.pc = * "Hex Routines"
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// ————————————————————————————————————
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// btohex
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// ————————————————————————————————————
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// ————————————————————————————————————
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// preparatory ops: .a: byte to convert
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//
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// returned values: .a: msn ascii char
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// .x: lsn ascii char
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// .y: entry value
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// ————————————————————————————————————
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byteToHex: pha //save byte
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and #%00001111 //extract lsn
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tax //save it
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pla //recover byte
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lsr //extract...
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lsr //msn
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lsr
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lsr
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pha //save msn
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txa //lsn
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jsr binhex1 //generate ascii lsn
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tax //save
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pla //get msn & fall thru
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//
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// convert nybble to hex ascii equivalent...
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binhex1: cmp #$0a
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bcc binhex2 //in decimal range
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sbc #$09 //hex compensate
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rts
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binhex2: eor #%00110000 //finalize nybble
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rts //done
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