/ SCCSID: @(#)aldiv.s 3.0 4/22/86 ////////////////////////////////////////////////////////////////////// / Copyright (c) Digital Equipment Corporation 1984, 1985, 1986. / / All Rights Reserved. / / Reference "/usr/src/COPYRIGHT" for applicable restrictions. / ////////////////////////////////////////////////////////////////////// / / Long quotient / Based on: (System V) aldiv.s 1.3 .globl aldiv .globl csv, cret aldiv: jsr r5,csv mov 8.(r5),r3 sxt r4 bpl 1f neg r3 bmi hardldiv 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,-(sp) /high quotient mov r1,r0 mov r2,r1 mov r0,r4 div r3,r0 bvc 1f mov r4,r0 mov r2,r1 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 (sp)+,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 17 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: clr -(sp) cmp r3,r0 bhi 1f blo 2f cmp 8.(r5),r1 bhi 1f 2: inc (sp) sub 8.(r5),r1 sbc r0 sub r3,r0 1: mov $16.,r4 1: clc rol r2 rol r1 rol r0 cmp r3,r0 bhi 3f blo 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 mov (sp)+,r0 tst (sp)+ beq 1f neg r0 neg r1 sbc r0 1: mov 4.(r5),r2 mov r0,(r2)+ mov r1,(r2) jmp cret