ref: 9ced712a2ad70557a8ceb89ff3b969b92c85f68c
dir: /sys/src/libc/68000/muldivrt.s/
/*
* calls _divul with
* absolute value arguments
*/
TEXT _divsl(SB), $0
MOVL R0, TOS
MOVL b+4(FP), R0
BPL y1
NEGL R0
MOVL R0, TOS
MOVL a+0(FP), R0
BPL y3
NEGL R0
MOVL R0, TOS
/* neg/neg */
JSR _divul(SB)
MOVL TOS, R0
MOVL R0, a+0(FP)
MOVL TOS, R0
NEGL R0
MOVL R0, b+4(FP)
MOVL TOS, R0
RTS
y1: MOVL R0, TOS
MOVL a+0(FP), R0
BPL y2
NEGL R0
MOVL R0, TOS
/* neg/pos */
JSR _divul(SB)
MOVL TOS, R0
NEGL R0
MOVL R0, a+0(FP)
MOVL TOS, R0
NEGL R0
MOVL R0, b+4(FP)
MOVL TOS, R0
RTS
y2: MOVL R0, TOS
/* pos/pos */
JSR _divul(SB)
MOVL TOS, R0
MOVL R0, a+0(FP)
MOVL TOS, R0
MOVL R0, b+4(FP)
MOVL TOS, R0
RTS
y3: MOVL R0, TOS
/* pos/neg */
JSR _divul(SB)
MOVL TOS, R0
NEGL R0
MOVL R0, a+0(FP)
MOVL TOS, R0
MOVL R0, b+4(FP)
MOVL TOS, R0
RTS
/*
* for(i=1;; i++) {
* if(den & (1<<31))
* break;
* den <<= 1;
* }
*
* for(; i; i--) {
* quo <<= 1;
* if(num >= den) {
* num -= den;
* quo |= 1;
* }
* den >>= 1;
* }
*/
TEXT _divul(SB), $0
MOVL R0, TOS /* i */
MOVL R1, TOS /* num */
MOVL R2, TOS /* den */
MOVL R3, TOS /* quo */
MOVL $0, R0
MOVL $0, R3
MOVL a+0(FP), R1
MOVL b+4(FP), R2
BEQ xout
BMI x1
ADDL $1, R0
LSLL $1, R2
BPL -2(PC)
x1: LSLL $1, R3
CMPL R1, R2
BCS 3(PC)
SUBL R2, R1
ORL $1, R3
LSRL $1, R2
DBMI R0, x1
MOVL R3, a+0(FP)
MOVL R1, b+4(FP)
xout:
MOVL TOS, R3
MOVL TOS, R2
MOVL TOS, R1
MOVL TOS, R0
RTS
/*
* x = 0;
* for(i=0; i<32; i++) {
* if(a & 1)
* x += b;
* a >>= 1;
* b <<= 1;
* }
* a = x;
*/
TEXT _mull(SB), $0
MOVL R0, TOS /* i */
MOVL R1, TOS /* a */
MOVL R2, TOS /* b */
MOVL R3, TOS /* x */
MOVL a+0(FP), R1
MOVL b+4(FP), R2
MOVL $32, R0
CLRL R3
z1: ROTRL $1, R1
BCC 2(PC)
ADDL R2, R3
LSLL $1, R2
DBEQ R0, z1
MOVL R3, b+4(FP)
MOVL TOS, R3
MOVL TOS, R2
MOVL TOS, R1
MOVL TOS, R0
RTS
TEXT _ccr(SB), $0
PEA (A0)
SUBL A0, A0
BCC 2(PC)
LEA 1(A0), A0
BVC 2(PC)
LEA 2(A0), A0
BNE 2(PC)
LEA 4(A0), A0
BPL 2(PC)
LEA 8(A0), A0
MOVW A0, a+0(FP)
MOVL TOS, A0
RTS