| /* SPDX-License-Identifier: GPL-2.0 */ |
| .section .text..SHmedia32,"ax" |
| .align 2 |
| .global __udivdi3 |
| __udivdi3: |
| shlri r3,1,r4 |
| nsb r4,r22 |
| shlld r3,r22,r6 |
| shlri r6,49,r5 |
| movi 0xffffffffffffbaf1,r21 /* .l shift count 17. */ |
| sub r21,r5,r1 |
| mmulfx.w r1,r1,r4 |
| mshflo.w r1,r63,r1 |
| sub r63,r22,r20 // r63 == 64 % 64 |
| mmulfx.w r5,r4,r4 |
| pta large_divisor,tr0 |
| addi r20,32,r9 |
| msub.w r1,r4,r1 |
| madd.w r1,r1,r1 |
| mmulfx.w r1,r1,r4 |
| shlri r6,32,r7 |
| bgt/u r9,r63,tr0 // large_divisor |
| mmulfx.w r5,r4,r4 |
| shlri r2,32+14,r19 |
| addi r22,-31,r0 |
| msub.w r1,r4,r1 |
| |
| mulu.l r1,r7,r4 |
| addi r1,-3,r5 |
| mulu.l r5,r19,r5 |
| sub r63,r4,r4 // Negate to make sure r1 ends up <= 1/r2 |
| shlri r4,2,r4 /* chop off leading %0000000000000000 001.00000000000 - or, as |
| the case may be, %0000000000000000 000.11111111111, still */ |
| muls.l r1,r4,r4 /* leaving at least one sign bit. */ |
| mulu.l r5,r3,r8 |
| mshalds.l r1,r21,r1 |
| shari r4,26,r4 |
| shlld r8,r0,r8 |
| add r1,r4,r1 // 31 bit unsigned reciprocal now in r1 (msb equiv. 0.5) |
| sub r2,r8,r2 |
| /* Can do second step of 64 : 32 div now, using r1 and the rest in r2. */ |
| |
| shlri r2,22,r21 |
| mulu.l r21,r1,r21 |
| shlld r5,r0,r8 |
| addi r20,30-22,r0 |
| shlrd r21,r0,r21 |
| mulu.l r21,r3,r5 |
| add r8,r21,r8 |
| mcmpgt.l r21,r63,r21 // See Note 1 |
| addi r20,30,r0 |
| mshfhi.l r63,r21,r21 |
| sub r2,r5,r2 |
| andc r2,r21,r2 |
| |
| /* small divisor: need a third divide step */ |
| mulu.l r2,r1,r7 |
| ptabs r18,tr0 |
| addi r2,1,r2 |
| shlrd r7,r0,r7 |
| mulu.l r7,r3,r5 |
| add r8,r7,r8 |
| sub r2,r3,r2 |
| cmpgt r2,r5,r5 |
| add r8,r5,r2 |
| /* could test r3 here to check for divide by zero. */ |
| blink tr0,r63 |
| |
| large_divisor: |
| mmulfx.w r5,r4,r4 |
| shlrd r2,r9,r25 |
| shlri r25,32,r8 |
| msub.w r1,r4,r1 |
| |
| mulu.l r1,r7,r4 |
| addi r1,-3,r5 |
| mulu.l r5,r8,r5 |
| sub r63,r4,r4 // Negate to make sure r1 ends up <= 1/r2 |
| shlri r4,2,r4 /* chop off leading %0000000000000000 001.00000000000 - or, as |
| the case may be, %0000000000000000 000.11111111111, still */ |
| muls.l r1,r4,r4 /* leaving at least one sign bit. */ |
| shlri r5,14-1,r8 |
| mulu.l r8,r7,r5 |
| mshalds.l r1,r21,r1 |
| shari r4,26,r4 |
| add r1,r4,r1 // 31 bit unsigned reciprocal now in r1 (msb equiv. 0.5) |
| sub r25,r5,r25 |
| /* Can do second step of 64 : 32 div now, using r1 and the rest in r25. */ |
| |
| shlri r25,22,r21 |
| mulu.l r21,r1,r21 |
| pta no_lo_adj,tr0 |
| addi r22,32,r0 |
| shlri r21,40,r21 |
| mulu.l r21,r7,r5 |
| add r8,r21,r8 |
| shlld r2,r0,r2 |
| sub r25,r5,r25 |
| bgtu/u r7,r25,tr0 // no_lo_adj |
| addi r8,1,r8 |
| sub r25,r7,r25 |
| no_lo_adj: |
| mextr4 r2,r25,r2 |
| |
| /* large_divisor: only needs a few adjustments. */ |
| mulu.l r8,r6,r5 |
| ptabs r18,tr0 |
| /* bubble */ |
| cmpgtu r5,r2,r5 |
| sub r8,r5,r2 |
| blink tr0,r63 |
| |
| /* Note 1: To shift the result of the second divide stage so that the result |
| always fits into 32 bits, yet we still reduce the rest sufficiently |
| would require a lot of instructions to do the shifts just right. Using |
| the full 64 bit shift result to multiply with the divisor would require |
| four extra instructions for the upper 32 bits (shift / mulu / shift / sub). |
| Fortunately, if the upper 32 bits of the shift result are nonzero, we |
| know that the rest after taking this partial result into account will |
| fit into 32 bits. So we just clear the upper 32 bits of the rest if the |
| upper 32 bits of the partial result are nonzero. */ |