NetBSD has kernel lib called libkern. It implements critical code like divide, So i had to implement divide. The implementation can be viewed/downloaded from: view: http://212.199.169.246/trac/file/netbsd/branches/nirm/src/sys/lib/libkern/arch/openrisc/divsi3.S download: http://212.199.169.246/trac/file/netbsd/branches/nirm/src/sys/lib/libkern/arch/openrisc/divsi3.S?rev=32&format=raw (All the sources can be browsed at http://212.199.169.246/trac, trac system is wiki/milestone/bug ticket system integrated with SubVersion version control system, svn access http://212.199.169.246/svn ) This is some of the code of L_udivide: L_udivide: l.sfeqi r4, 0 /* check if divisor 0 */ l.bf L_overflow l.sfeqi r4, 1 /* check if divisor 1 */ l.bf L_divide_l1 l.sfeqi r3, 0 /* check if dividend 0 */ l.bf L_divide_l2 l.sfeqi r3, 1 /* check if dividend 1 */ l.bf L_divide_l3 l.sfeq r3, r4 /* check if dividend = divisor */ l.bf L_divide_l4 l.addi r11, r3, 0 l.addi r15, r4, 0 L_divide_l0: L_divide_b31: l.srli r12, r11, 31 /* Set remainder LSB from divisor MSB */ l.slli r11, r11, 1 /* Left shit dividend */ l.sfltu r12, r15 /* Is remainder less then divisor */ l.bf L_divide_b30 /* If so skip to next bit */ l.srli r13, r11, 31 /* Delay slot get MSB of quotient */ l.sub r12, r12, r15 /* Substruct divisor from remainder */ l.addi r11, r11, 1 /* Set remainder LSB to 1 */ L_divide_b30: l.slli r12, r12, 1 /* Left shit remainder */ l.slli r11, r11, 1 /* Left shit quotient */ l.add r12, r12, r13 /* Set remainder LSB from quotient MSB */ l.sfltu r12, r15 /* Is remainder less then divisor */ l.bf L_divide_b29 /* If so skip to next bit */ l.srli r13, r11, 31 /* Delay slot get MSB of remainder */ l.sub r12, r12, r15 /* Substruct divisor from remainder */ l.addi r11, r11, 1 /* Set remainder LSB to 1 */ L_divide_b29: