;-----------------------------------------------------------------------------: ; 8bit/8bit Unsigned Division ; ; Register Variables ; Call: var1 = dividend (0x00..0xff) ; var2 = divisor (0x01..0x7f) ; mod = <don't care> ; lc = <don't care> (high register must be allocated) ; ; Result:var1 = var1 / var2 ; var2 = <not changed> ; mod = var1 % var2 ; lc = 0 ; ; Size = 11 words ; Clock = 66..74 cycles (+ret) ; Stack = 0 byte div08u: clr mod ;initialize variables ldi lc,8 ; mod = 0; lc = 8; ;---- calculating loop lsl var1 ;var1 = var1 << 1; rol mod ;mod = mod << 1 + carry; cp mod,var2 ;if (mod => var2) { brcs PC+3 ; mod -= var2; var1++; inc var1 ; } sub mod,var2 ;/ dec lc ;if (--lc > 0) brne PC-7 ; continue loop; ret
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Ashley Roll has put together a really nice little unit here. Leave off the MAX232 and keep these handy for the few times you need true RS232! |
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