/ Long quotient .globl aldiv .globl csv, cret aldiv: jsr r5,csv mov 8.(r5),r3 sxt r4 bpl 1f neg r3 1: cmp r4,6.(r5) bne hardldiv mov 4(r5),r1 mov 2(r1),r2 mov (r1),r1 bge 1f neg r1 neg r2 sbc r1 com r4 1: mov r4,-(sp) clr r0 div r3,r0 mov r0,r4 /high quotient mov r1,r0 mov r2,r1 div r3,r0 bvc 1f sub r3,r0 / this is the clever part div r3,r0 tst r1 sxt r1 add r1,r0 / cannot overflow! 1: mov r0,r1 mov r4,r0 tst (sp)+ bpl 9f neg r0 neg r1 sbc r0 9: mov 4.(r5),r2 mov r0,(r2)+ mov r1,(r2) jmp cret / The divisor is known to be >= 2^15 so only 16 cycles are needed. hardldiv: clr -(sp) mov 4.(r5),r0 mov 2(r0),r2 mov (r0),r1 bpl 1f com (sp) neg r1 neg r2 sbc r1 1: clr r0 mov 6.(r5),r3 bge 1f neg r3 neg 8.(r5) sbc r3 com (sp) 1: mov $16.,r4 1: clc rol r2 rol r1 rol r0 cmp r3,r0 bgt 3f blt 2f cmp 8.(r5),r1 blos 2f 3: sob r4,1b br 1f 2: sub 8.(r5),r1 sbc r0 sub r3,r0 inc r2 sob r4,1b 1: mov r2,r1 clr r0 tst (sp)+ beq 1f neg r0 neg r1 sbc r0 1: mov 4.(r5),r2 mov r0,(r2)+ mov r1,(r2) jmp cret