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+# IBM POWER __mpn_sub_n -- Subtract two limb vectors of equal, non-zero length.
+
+# Copyright (C) 1992, 1994, 1995, 1996 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 Lesser General Public License as published by
+# the Free Software Foundation; either version 2.1 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 Lesser General Public
+# License for more details.
+
+# You should have received a copy of the GNU Lesser 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:
+ andil. 10,6,1 # odd or even number of limbs?
+ l 8,0(4) # load least significant s1 limb
+ l 0,0(5) # load least significant s2 limb
+ cal 3,-4(3) # offset res_ptr, it's updated before it's used
+ sri 10,6,1 # count for unrolled loop
+ sf 7,0,8 # subtract least significant limbs, set cy
+ mtctr 10 # copy count into CTR
+ beq 0,Leven # branch if even # of limbs (# of limbs >= 2)
+
+# We have an odd # of limbs. Add the first limbs separately.
+ cmpi 1,10,0 # is count for unrolled loop zero?
+ bne 1,L1 # branch if not
+ st 7,4(3)
+ sfe 3,0,0 # load !cy into ...
+ sfi 3,3,0 # ... return value register
+ br # return
+
+# We added least significant limbs. Now reload the next limbs to enter loop.
+L1: lu 8,4(4) # load s1 limb and update s1_ptr
+ lu 0,4(5) # load s2 limb and update s2_ptr
+ stu 7,4(3)
+ sfe 7,0,8 # subtract limbs, set cy
+Leven: lu 9,4(4) # load s1 limb and update s1_ptr
+ lu 10,4(5) # load s2 limb and update s2_ptr
+ bdz Lend # If done, skip loop
+
+Loop: lu 8,4(4) # load s1 limb and update s1_ptr
+ lu 0,4(5) # load s2 limb and update s2_ptr
+ sfe 11,10,9 # subtract previous limbs with cy, set cy
+ stu 7,4(3) #
+ lu 9,4(4) # load s1 limb and update s1_ptr
+ lu 10,4(5) # load s2 limb and update s2_ptr
+ sfe 7,0,8 # subtract previous limbs with cy, set cy
+ stu 11,4(3) #
+ bdn Loop # decrement CTR and loop back
+
+Lend: sfe 11,10,9 # subtract limbs with cy, set cy
+ st 7,4(3) #
+ st 11,8(3) #
+ sfe 3,0,0 # load !cy into ...
+ sfi 3,3,0 # ... return value register
+ br