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Q = 0
N = 1
D = 2
CC = 3
TMP = 11
TEXT save<>(SB), 1, $0
MOVW R(Q), 0(FP)
MOVW R(N), 4(FP)
MOVW R(D), 8(FP)
MOVW R(CC), 12(FP)
MOVW R(TMP), R(Q) /* numerator */
MOVW 20(FP), R(D) /* denominator */
CMP $0, R(D)
BNE s1
MOVW -1(R(D)), R(TMP) /* divide by zero fault */
s1: RET
TEXT rest<>(SB), 1, $0
MOVW 0(FP), R(Q)
MOVW 4(FP), R(N)
MOVW 8(FP), R(D)
MOVW 12(FP), R(CC)
/*
* return to caller
* of rest<>
*/
MOVW 0(R13), R14
ADD $20, R13
B (R14)
TEXT div<>(SB), 1, $0
MOVW $32, R(CC)
/*
* skip zeros 8-at-a-time
*/
e1:
AND.S $(0xff<<24),R(Q), R(N)
BNE e2
SLL $8, R(Q)
SUB.S $8, R(CC)
BNE e1
RET
e2:
MOVW $0, R(N)
loop:
/*
* shift R(N||Q) left one
*/
SLL $1, R(N)
CMP $0, R(Q)
ORR.LT $1, R(N)
SLL $1, R(Q)
/*
* compare numerator to denominator
* if less, subtract and set quotent bit
*/
CMP R(D), R(N)
ORR.HS $1, R(Q)
SUB.HS R(D), R(N)
SUB.S $1, R(CC)
BNE loop
RET
TEXT _div(SB), 1, $16
BL save<>(SB)
CMP $0, R(Q)
BGE d1
RSB $0, R(Q), R(Q)
CMP $0, R(D)
BGE d2
RSB $0, R(D), R(D)
d0:
BL div<>(SB) /* none/both neg */
MOVW R(Q), R(TMP)
B out
d1:
CMP $0, R(D)
BGE d0
RSB $0, R(D), R(D)
d2:
BL div<>(SB) /* one neg */
RSB $0, R(Q), R(TMP)
B out
TEXT _mod(SB), 1, $16
BL save<>(SB)
CMP $0, R(D)
RSB.LT $0, R(D), R(D)
CMP $0, R(Q)
BGE m1
RSB $0, R(Q), R(Q)
BL div<>(SB) /* neg numerator */
RSB $0, R(N), R(TMP)
B out
m1:
BL div<>(SB) /* pos numerator */
MOVW R(N), R(TMP)
B out
TEXT _divu(SB), 1, $16
BL save<>(SB)
BL div<>(SB)
MOVW R(Q), R(TMP)
B out
TEXT _modu(SB), 1, $16
BL save<>(SB)
BL div<>(SB)
MOVW R(N), R(TMP)
B out
out:
BL rest<>(SB)
B out
|
