diff options
Diffstat (limited to 'lib_arm/_umodsi3.S')
| -rw-r--r-- | lib_arm/_umodsi3.S | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/lib_arm/_umodsi3.S b/lib_arm/_umodsi3.S new file mode 100644 index 0000000..899ffbf --- /dev/null +++ b/lib_arm/_umodsi3.S @@ -0,0 +1,88 @@ +/* # 1 "libgcc1.S" */ +@ libgcc1 routines for ARM cpu. +@ Division routines, written by Richard Earnshaw, (rearnsha@armltd.co.uk) +/* # 145 "libgcc1.S" */ +dividend .req r0 +divisor .req r1 +overdone .req r2 +curbit .req r3 +ip .req r12 +sp .req r13 +lr .req r14 +pc .req r15 + .text + .globl __umodsi3 + .type __umodsi3 ,function + .align 0 + __umodsi3 : + cmp divisor, #0 + beq Ldiv0 + mov curbit, #1 + cmp dividend, divisor + movcc pc, lr +Loop1: + @ Unless the divisor is very big, shift it up in multiples of + @ four bits, since this is the amount of unwinding in the main + @ division loop. Continue shifting until the divisor is + @ larger than the dividend. + cmp divisor, #0x10000000 + cmpcc divisor, dividend + movcc divisor, divisor, lsl #4 + movcc curbit, curbit, lsl #4 + bcc Loop1 +Lbignum: + @ For very big divisors, we must shift it a bit at a time, or + @ we will be in danger of overflowing. + cmp divisor, #0x80000000 + cmpcc divisor, dividend + movcc divisor, divisor, lsl #1 + movcc curbit, curbit, lsl #1 + bcc Lbignum +Loop3: + @ Test for possible subtractions. On the final pass, this may + @ subtract too much from the dividend, so keep track of which + @ subtractions are done, we can fix them up afterwards... + mov overdone, #0 + cmp dividend, divisor + subcs dividend, dividend, divisor + cmp dividend, divisor, lsr #1 + subcs dividend, dividend, divisor, lsr #1 + orrcs overdone, overdone, curbit, ror #1 + cmp dividend, divisor, lsr #2 + subcs dividend, dividend, divisor, lsr #2 + orrcs overdone, overdone, curbit, ror #2 + cmp dividend, divisor, lsr #3 + subcs dividend, dividend, divisor, lsr #3 + orrcs overdone, overdone, curbit, ror #3 + mov ip, curbit + cmp dividend, #0 @ Early termination? + movnes curbit, curbit, lsr #4 @ No, any more bits to do? + movne divisor, divisor, lsr #4 + bne Loop3 + @ Any subtractions that we should not have done will be recorded in + @ the top three bits of "overdone". Exactly which were not needed + @ are governed by the position of the bit, stored in ip. + @ If we terminated early, because dividend became zero, + @ then none of the below will match, since the bit in ip will not be + @ in the bottom nibble. + ands overdone, overdone, #0xe0000000 + moveq pc, lr @ No fixups needed + tst overdone, ip, ror #3 + addne dividend, dividend, divisor, lsr #3 + tst overdone, ip, ror #2 + addne dividend, dividend, divisor, lsr #2 + tst overdone, ip, ror #1 + addne dividend, dividend, divisor, lsr #1 + mov pc, lr +Ldiv0: + str lr, [sp, #-4]! + bl __div0 (PLT) + mov r0, #0 @ about as wrong as it could be + ldmia sp!, {pc} + .size __umodsi3 , . - __umodsi3 +/* # 320 "libgcc1.S" */ +/* # 421 "libgcc1.S" */ +/* # 433 "libgcc1.S" */ +/* # 456 "libgcc1.S" */ +/* # 500 "libgcc1.S" */ +/* # 580 "libgcc1.S" */ |