1 files changed, 58 insertions, 0 deletions

diff --git a/arch/powerpc/lib/div64.S b/arch/powerpc/lib/div64.S
new file mode 100644
index 000000000000..3527569e9926
--- /dev/null
+++ b/arch/powerpc/lib/div64.S
@@ -0,0 +1,58 @@
+/*
+ * Divide a 64-bit unsigned number by a 32-bit unsigned number.
+ * This routine assumes that the top 32 bits of the dividend are
+ * non-zero to start with.
+ * On entry, r3 points to the dividend, which get overwritten with
+ * the 64-bit quotient, and r4 contains the divisor.
+ * On exit, r3 contains the remainder.
+ *
+ * Copyright (C) 2002 Paul Mackerras, IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+#include <asm/ppc_asm.h>
+#include <asm/processor.h>
+
+_GLOBAL(__div64_32)
+        lwz     r5,0(r3)        # get the dividend into r5/r6
+        lwz     r6,4(r3)
+        cmplw   r5,r4
+        li      r7,0
+        li      r8,0
+        blt     1f
+        divwu   r7,r5,r4        # if dividend.hi >= divisor,
+        mullw   r0,r7,r4        # quotient.hi = dividend.hi / divisor
+        subf.   r5,r0,r5        # dividend.hi %= divisor
+        beq     3f
+1:      mr      r11,r5          # here dividend.hi != 0
+        andis.  r0,r5,0xc000
+        bne     2f
+        cntlzw  r0,r5           # we are shifting the dividend right
+        li      r10,-1          # to make it < 2^32, and shifting
+        srw     r10,r10,r0      # the divisor right the same amount,
+        add     r9,r4,r10       # rounding up (so the estimate cannot
+        andc    r11,r6,r10      # ever be too large, only too small)
+        andc    r9,r9,r10
+        or      r11,r5,r11
+        rotlw   r9,r9,r0
+        rotlw   r11,r11,r0
+        divwu   r11,r11,r9      # then we divide the shifted quantities
+2:      mullw   r10,r11,r4      # to get an estimate of the quotient,
+        mulhwu  r9,r11,r4       # multiply the estimate by the divisor,
+        subfc   r6,r10,r6       # take the product from the divisor,
+        add     r8,r8,r11       # and add the estimate to the accumulated
+        subfe.  r5,r9,r5        # quotient
+        bne     1b
+3:      cmplw   r6,r4
+        blt     4f
+        divwu   r0,r6,r4        # perform the remaining 32-bit division
+        mullw   r10,r0,r4       # and get the remainder
+        add     r8,r8,r0
+        subf    r6,r10,r6
+4:      stw     r7,0(r3)        # return the quotient in *r3
+        stw     r8,4(r3)
+        mr      r3,r6           # return the remainder in r3
+        blr