1/* udiv.s 4.2 83/06/27 */ 2 3/* 4 * udiv - unsigned division for vax-11 5 * 6 * arguments: dividend, divisor. 7 * result: quotient. 8 * uses r0-r2 9 * 10 * If 1 < divisor <= 2147483647, zero-extend the dividend 11 * to 64 bits and let ediv do the work. If the divisor is 1, 12 * ediv will overflow if bit 31 of the dividend is on, so 13 * just return the dividend unchanged. If the divisor is 0, 14 * do the ediv also, so it will generate the proper exception. 15 * All other values of the divisor have bit 31 on: in this case 16 * the quotient must be 0 if divisor > dividend, and 1 otherwise, 17 * provided that the comparison is made as unsigned. 18 */ 19 20#include "DEFS.h" 21 22ASENTRY(udiv) 23 movl 4(ap),r0 /* dividend */ 24 movl 8(ap),r2 /* divisor */ 25 jeql 1f /* if divisor=0, force exception */ 26 cmpl r2,$1 /* if divisor <= 1 (signed), */ 27 jleq 2f /* no division is necessary */ 281: 29 clrl r1 /* zero-extend the dividend */ 30 ediv r2,r0,r0,r2 /* divide. q->r0, r->r2 (discarded) */ 31 ret 322: 33 jeql 1f /* if divisor=1, return dividend */ 34 cmpl r0,r2 /* unsigned comparison between */ 35 jgequ 2f /* dividend and divisor */ 36 clrl r0 /* dividend < divisor, return 0 */ 37 ret 382: 39 movl $1,r0 /* dividend >= divisor, return 1 */ 401: 41 ret 42