# # udiv - unsigned division for vax-11 # # arguments: dividend, divisor. # result: quotient. # uses r0-r2 # # If 1 < divisor <= 2147483647, zero-extend the dividend # to 64 bits and let ediv do the work. If the divisor is 1, # ediv will overflow if bit 31 of the dividend is on, so # just return the dividend unchanged. If the divisor is 0, # do the ediv also, so it will generate the proper exception. # All other values of the divisor have bit 31 on: in this case # the quotient must be 0 if divisor > dividend, and 1 otherwise, # provided that the comparison is made as unsigned. # .text .align 1 .globl udiv udiv: .word 0x0000 movl 4(ap),r0 # Dividend movl 8(ap),r2 # Divisor jeql div # If divisor=0, force exception cmpl r2,$1 # If divisor <= 1 (signed), jleq nodiv # no division is necessary div: clrl r1 # Zero-extend the dividend ediv r2,r0,r0,r2 # Divide. q->r0, r->r2 (discarded) ret nodiv: jeql retn # If divisor=1, return dividend cmpl r0,r2 # Unsigned comparison between jgequ one # dividend and divisor clrl r0 # Dividend < divisor, return 0 ret one: movl $1,r0 # Dividend >= divisor, return 1 retn: ret