1 files changed, 69 insertions, 0 deletions
diff --git a/sysdeps/powerpc/sub_n.s b/sysdeps/powerpc/sub_n.s
new file mode 100644
index 0000000000..8711bf9a40
--- /dev/null
+++ b/sysdeps/powerpc/sub_n.s
@@ -0,0 +1,69 @@
+ # Subtract two limb vectors of equal, non-zero length for PowerPC.
+ # Copyright (C) 1997 Free Software Foundation, Inc.
+ # This file is part of the GNU C Library.
+ #
+ # The GNU C Library is free software; you can redistribute it and/or
+ # modify it under the terms of the GNU Library General Public License as
+ # published by the Free Software Foundation; either version 2 of the
+ # License, or (at your option) any later version.
+ #
+ # The GNU C Library is distributed in the hope that it will be useful,
+ # but WITHOUT ANY WARRANTY; without even the implied warranty of
+ # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ # Library General Public License for more details.
+ #
+ # You should have received a copy of the GNU Library General Public
+ # License along with the GNU C Library; see the file COPYING.LIB.  If not,
+ # write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ # Boston, MA 02111-1307, USA.
+
+ # mp_limb_t mpn_sub_n (mp_ptr res_ptr, mp_srcptr s1_ptr, mp_srcptr s2_ptr,
+ #                      mp_size_t size)
+ # Calculate s1-s2 and put result in res_ptr; return borrow, 0 or 1.
+
+ # Note on optimisation: This code is optimal for the 601.  Almost every other
+ # possible 2-unrolled inner loop will not be.  Also, watch out for the
+ # alignment...
+
+	.align 3
+	.globl __mpn_sub_n
+	.type	 __mpn_sub_n,@function
+	nop
+__mpn_sub_n:
+ # Set up for loop below.
+	mtcrf 0x01,%r6
+	srwi. %r7,%r6,1
+	mtctr %r7
+	bt    31,2f
+
+ # Set the carry (clear the borrow).
+	subfc %r0,%r0,%r0
+ # Adjust pointers for loop.
+	addi  %r3,%r3,-4
+	addi  %r4,%r4,-4
+	addi  %r5,%r5,-4
+	b     0f
+
+2:	lwz   %r7,0(%r5)
+	lwz   %r6,0(%r4)
+	subfc %r6,%r7,%r6
+	stw   %r6,0(%r3)
+        beq   1f
+
+ # Align start of loop to an odd word boundary to guarantee that the
+ # last two words can be fetched in one access (for 601).  This turns
+ # out to be important.
+0:
+	lwz   %r9,4(%r4)
+	lwz   %r8,4(%r5)
+	lwzu  %r6,8(%r4)
+	lwzu  %r7,8(%r5)
+	subfe %r8,%r8,%r9
+	stw   %r8,4(%r3)
+	subfe %r6,%r7,%r6
+	stwu  %r6,8(%r3)
+	bdnz  0b
+ # return the borrow
+1:	subfe %r3,%r3,%r3
+	neg   %r3,%r3
+	blr