libzahl

commit 659a5a81045af899310dca5f70907da287c56d19
parent 8cfddc81a437ec86fdf3afd2156eac8bd78f88b8
Author: Mattias Andrée <maandree@kth.se>
Date:   Wed, 27 Apr 2016 14:35:13 +0200

Optimise zpowu and zmodpowu

Signed-off-by: Mattias Andrée <maandree@kth.se>

Diffstat:
M
src/zmodpowu.c
 | 
6
++++--
M
src/zpowu.c
 | 
6
++++--

2 files changed, 8 insertions(+), 4 deletions(-)
diff --git a/src/zmodpowu.c b/src/zmodpowu.c
@@ -27,9 +27,11 @@ zmodpowu(z_t a, z_t b, unsigned long long int c, z_t d)
 	zset(td, d);
 	zsetu(a, 1);
 
-	for (; c; c >>= 1) {
+	if (c & 1)
+		zmodmul(a, a, tb, td);
+	while (c >>= 1) {
+		zmodsqr(tb, tb, td);
 		if (c & 1)
 			zmodmul(a, a, tb, td);
-		zmodsqr(tb, tb, td);
 	}
 }
diff --git a/src/zpowu.c b/src/zpowu.c
@@ -23,10 +23,12 @@ zpowu(z_t a, z_t b, unsigned long long int c)
 	zabs(tb, b);
 	zsetu(a, 1);
 
-	for (; c; c >>= 1) {
+	if (c & 1)
+		zmul_impl(a, a, tb);
+	while (c >>= 1) {
+		zsqr_impl(tb, tb);
 		if (c & 1)
 			zmul_impl(a, a, tb);
-		zsqr_impl(tb, tb);
 	}
 
 	if (neg)