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-rw-r--r--src/zlsh.c30
1 files changed, 16 insertions, 14 deletions
diff --git a/src/zlsh.c b/src/zlsh.c
index b631c1a..2a76fbc 100644
--- a/src/zlsh.c
+++ b/src/zlsh.c
@@ -19,25 +19,27 @@ zlsh(z_t a, z_t b, size_t bits)
chars = FLOOR_BITS_TO_CHARS(bits);
bits = BITS_IN_LAST_CHAR(bits);
- cbits = BITS_PER_CHAR - 1 - bits;
+ cbits = BITS_PER_CHAR - bits;
- a->used = b->used + chars;
- ENSURE_SIZE(a, a->used);
+ ENSURE_SIZE(a, b->used + chars);
if (a == b)
- zmemmove(a->chars + chars, b->chars, a->used);
+ zmemmove(a->chars + chars, b->chars, b->used);
else
- zmemcpy(a->chars + chars, b->chars, a->used);
+ zmemcpy(a->chars + chars, b->chars, b->used);
zmemset(a->chars, 0, chars);
+ a->used = b->used + chars;
- for (i = chars; i < a->used; i++) {
- carry[~i & 1] = a->chars[i] >> cbits;
- a->chars[i] <<= bits;
- a->chars[i] |= carry[i & 1];
- }
- if (carry[i & 1]) {
- ENSURE_SIZE(a, a->alloced << 1);
- a->chars[i] = carry[i & 1];
- a->used++;
+ if (bits) { /* This if statement is very important in C. */
+ for (i = chars; i < a->used; i++) {
+ carry[~i & 1] = 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++;
+ }
}
SET_SIGNUM(a, zsignum(b));