summaryrefslogtreecommitdiff
path: root/arch/sh/lib64/udivdi3.S
diff options
context:
space:
mode:
Diffstat (limited to 'arch/sh/lib64/udivdi3.S')
-rw-r--r--arch/sh/lib64/udivdi3.S120
1 files changed, 120 insertions, 0 deletions
diff --git a/arch/sh/lib64/udivdi3.S b/arch/sh/lib64/udivdi3.S
new file mode 100644
index 000000000000..6895c0225b85
--- /dev/null
+++ b/arch/sh/lib64/udivdi3.S
@@ -0,0 +1,120 @@
+ .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. */