Optimisations

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

1 files changed, 7 insertions, 13 deletions

diff --git a/src/zlsh.c b/src/zlsh.c
index 42894e0..1c9fd8f 100644
--- a/src/zlsh.c
+++ b/src/zlsh.c
@@ -6,22 +6,18 @@ void
 zlsh(z_t a, z_t b, size_t bits)
 {
 	size_t i, chars, cbits;
-	zahl_char_t carry[] = {0, 0};
+	zahl_char_t carry = 0, tcarry;
 
 	if (unlikely(zzero(b))) {
 		SET_SIGNUM(a, 0);
 		return;
 	}
-	if (unlikely(!bits)) {
-		SET(a, b);
-		return;
-	}
 
 	chars = FLOOR_BITS_TO_CHARS(bits);
 	bits = BITS_IN_LAST_CHAR(bits);
 	cbits = BITS_PER_CHAR - bits;
 
-	ENSURE_SIZE(a, b->used + chars);
+	ENSURE_SIZE(a, b->used + chars + 1);
 	if (likely(a == b))
 		zmemmove(a->chars + chars, b->chars, b->used);
 	else
@@ -31,15 +27,13 @@ zlsh(z_t a, z_t b, size_t bits)
 
 	if (likely(bits)) { /* This if statement is very important in C. */
 		for (i = chars; i < a->used; i++) {
-			carry[~i & 1] = a->chars[i] >> cbits;
+			tcarry = a->chars[i] >> cbits;
 			a->chars[i] <<= bits;
-			a->chars[i] |= carry[i & 1];
-		}
-		if (carry[i & 1]) {
-			ENSURE_SIZE(a, a->used + 1);
-			a->chars[i] = carry[i & 1];
-			a->used++;
+			a->chars[i] |= carry;
+			carry = tcarry;
 		}
+		if (carry)
+			a->chars[a->used++] = carry;
 	}
 
 	SET_SIGNUM(a, zsignum(b));