From 5860237d2f05f6ae45a98569b0d567c2227904c6 Mon Sep 17 00:00:00 2001 From: Mattias Andrée Date: Sat, 5 Mar 2016 20:16:14 +0100 Subject: Fix bugs and add a randomised testing MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Signed-off-by: Mattias Andrée --- src/zsub.c | 39 ++++++++++++++++++++++++++++++--------- 1 file changed, 30 insertions(+), 9 deletions(-) (limited to 'src/zsub.c') diff --git a/src/zsub.c b/src/zsub.c index 8616542..5096eb0 100644 --- a/src/zsub.c +++ b/src/zsub.c @@ -5,28 +5,49 @@ void zsub_unsigned(z_t a, z_t b, z_t c) { - int magcmp = zcmpmag(b, c); - z_t s; - size_t i, n; zahl_char_t carry[] = {0, 0}; + zahl_char_t *s; + size_t i, n; + int magcmp; + + if (zzero(b)) { + zabs(a, c); + zneg(a, a); + return; + } else if (zzero(c)) { + zabs(a, b); + return; + } else if (a == b || a == c) { + /* TODO This should not be necessary. */ + z_t tb, tc; + zinit(tb); + zinit(tc); + zset(tb, b); + zset(tc, c); + zsub_unsigned(a, tb, tc); + zfree(tb); + zfree(tc); + return; + } + magcmp = zcmpmag(b, c); if (magcmp <= 0) { if (magcmp == 0) { SET_SIGNUM(a, 0); return; } SET(a, c); - *s = *b; + n = MIN(a->used, b->used); + s = b->chars; } else { SET(a, b); - *s = *c; + n = MIN(a->used, c->used); + s = c->chars; } - n = MIN(a->used, s->used); - for (i = 0; i < n; i++) { - carry[~i & 1] = carry[i & 1] ? (a->chars[i] <= s->chars[i]) : (a->chars[i] < s->chars[i]); - a->chars[i] -= s->chars[i]; + carry[~i & 1] = carry[i & 1] ? (a->chars[i] <= s[i]) : (a->chars[i] < s[i]); + a->chars[i] -= s[i]; a->chars[i] -= carry[i & 1]; } -- cgit v1.2.3-70-g09d2