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+# PowerPC-32 __mpn_sub_n -- Subtract two limb vectors of the same length > 0
+# and store difference in a third limb vector.
+
+# Copyright (C) 1992, 1994, 1995 Free Software Foundation, Inc.
+
+# This file is part of the GNU MP Library.
+
+# The GNU MP 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 MP 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 MP 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.
+
+
+# INPUT PARAMETERS
+# res_ptr r3
+# s1_ptr r4
+# s2_ptr r5
+# size r6
+
+ .toc
+ .extern __mpn_sub_n[DS]
+ .extern .__mpn_sub_n
+.csect [PR]
+ .align 2
+ .globl __mpn_sub_n
+ .globl .__mpn_sub_n
+ .csect __mpn_sub_n[DS]
+__mpn_sub_n:
+ .long .__mpn_sub_n, TOC[tc0], 0
+ .csect [PR]
+.__mpn_sub_n:
+ mtctr 6 # copy size into CTR
+ lwz 8,0(4) # load least significant s1 limb
+ lwz 0,0(5) # load least significant s2 limb
+ addi 3,3,-4 # offset res_ptr, it's updated before used
+ subfc 7,0,8 # add least significant limbs, set cy
+ bdz Lend # If done, skip loop
+Loop: lwzu 8,4(4) # load s1 limb and update s1_ptr
+ lwzu 0,4(5) # load s2 limb and update s2_ptr
+ stwu 7,4(3) # store previous limb in load latency slot
+ subfe 7,0,8 # add new limbs with cy, set cy
+ bdn Loop # decrement CTR and loop back
+Lend: stw 7,4(3) # store ultimate result limb
+ subfe 3,0,0 # load !cy into ...
+ subfic 3,3,0 # ... return value register
+ blr