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authorKibum Kim <kb0929.kim@samsung.com>2012-01-07 00:46:38 +0900
committerKibum Kim <kb0929.kim@samsung.com>2012-01-07 00:46:38 +0900
commitf5660c6460a863b19f9ef745575780e37cc192a9 (patch)
tree0b478679da32d706de7b0de546d2e4daf03b160c /mpi/power/mpih-mul3.S
parent06b9124a4f9d38acc78e6af686bc49a06f6354f8 (diff)
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+/* IBM POWER submul_1 -- Multiply a limb vector with a limb and subtract
+ * the result from a second limb vector.
+ *
+ * Copyright (C) 1992, 1994, 1999 Free Software Foundation, Inc.
+ *
+ * This file is part of GnuPG.
+ *
+ * GnuPG 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.
+ *
+ * GnuPG 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
+ * USA.
+ */
+
+#include "sysdep.h"
+#include "asm-syntax.h"
+
+
+/*
+
+# INPUT PARAMETERS
+# res_ptr r3
+# s1_ptr r4
+# size r5
+# s2_limb r6
+
+# The RS/6000 has no unsigned 32x32->64 bit multiplication instruction. To
+# obtain that operation, we have to use the 32x32->64 signed multiplication
+# instruction, and add the appropriate compensation to the high limb of the
+# result. We add the multiplicand if the multiplier has its most significant
+# bit set, and we add the multiplier if the multiplicand has its most
+# significant bit set. We need to preserve the carry flag between each
+# iteration, so we have to compute the compensation carefully (the natural,
+# srai+and doesn't work). Since the POWER architecture has a branch unit
+# we can branch in zero cycles, so that's how we perform the additions.
+ */
+
+ .toc
+ .csect .mpihelp_submul_1[PR]
+ .align 2
+ .globl mpihelp_submul_1
+ .globl .mpihelp_submul_1
+ .csect mpihelp_submul_1[DS]
+mpihelp_submul_1:
+ .long .mpihelp_submul_1[PR], TOC[tc0], 0
+ .csect .mpihelp_submul_1[PR]
+.mpihelp_submul_1:
+
+ cal 3,-4(3)
+ l 0,0(4)
+ cmpi 0,6,0
+ mtctr 5
+ mul 9,0,6
+ srai 7,0,31
+ and 7,7,6
+ mfmq 11
+ cax 9,9,7
+ l 7,4(3)
+ sf 8,11,7 # add res_limb
+ a 11,8,11 # invert cy (r11 is junk)
+ blt Lneg
+Lpos: bdz Lend
+
+Lploop: lu 0,4(4)
+ stu 8,4(3)
+ cmpi 0,0,0
+ mul 10,0,6
+ mfmq 0
+ ae 11,0,9 # low limb + old_cy_limb + old cy
+ l 7,4(3)
+ aze 10,10 # propagate cy to new cy_limb
+ sf 8,11,7 # add res_limb
+ a 11,8,11 # invert cy (r11 is junk)
+ bge Lp0
+ cax 10,10,6 # adjust high limb for negative limb from s1
+Lp0: bdz Lend0
+ lu 0,4(4)
+ stu 8,4(3)
+ cmpi 0,0,0
+ mul 9,0,6
+ mfmq 0
+ ae 11,0,10
+ l 7,4(3)
+ aze 9,9
+ sf 8,11,7
+ a 11,8,11 # invert cy (r11 is junk)
+ bge Lp1
+ cax 9,9,6 # adjust high limb for negative limb from s1
+Lp1: bdn Lploop
+
+ b Lend
+
+Lneg: cax 9,9,0
+ bdz Lend
+Lnloop: lu 0,4(4)
+ stu 8,4(3)
+ cmpi 0,0,0
+ mul 10,0,6
+ mfmq 7
+ ae 11,7,9
+ l 7,4(3)
+ ae 10,10,0 # propagate cy to new cy_limb
+ sf 8,11,7 # add res_limb
+ a 11,8,11 # invert cy (r11 is junk)
+ bge Ln0
+ cax 10,10,6 # adjust high limb for negative limb from s1
+Ln0: bdz Lend0
+ lu 0,4(4)
+ stu 8,4(3)
+ cmpi 0,0,0
+ mul 9,0,6
+ mfmq 7
+ ae 11,7,10
+ l 7,4(3)
+ ae 9,9,0 # propagate cy to new cy_limb
+ sf 8,11,7 # add res_limb
+ a 11,8,11 # invert cy (r11 is junk)
+ bge Ln1
+ cax 9,9,6 # adjust high limb for negative limb from s1
+Ln1: bdn Lnloop
+ b Lend
+
+Lend0: cal 9,0(10)
+Lend: st 8,4(3)
+ aze 3,9
+ br
+