py: Fix rshift and not of zero/one edge cases in mpz.
Addresses issue #1027.
diff --git a/py/mpz.c b/py/mpz.c
index fc1109f..6213b4a 100644
--- a/py/mpz.c
+++ b/py/mpz.c
@@ -871,11 +871,17 @@
if (dest != z) {
mpz_set(dest, z);
}
- if (dest->neg) {
+ if (dest->len == 0) {
+ mpz_need_dig(dest, 1);
+ dest->dig[0] = 1;
+ dest->len = 1;
+ dest->neg = 1;
+ } else if (dest->neg) {
dest->neg = 0;
mpz_dig_t k = 1;
dest->len = mpn_sub(dest->dig, dest->dig, dest->len, &k, 1);
} else {
+ mpz_need_dig(dest, dest->len + 1);
mpz_dig_t k = 1;
dest->len = mpn_add(dest->dig, dest->dig, dest->len, &k, 1);
dest->neg = 1;
@@ -924,7 +930,14 @@
round_up = 1;
}
if (round_up) {
- dest->len = mpn_add(dest->dig, dest->dig, dest->len, &round_up, 1);
+ if (dest->len == 0) {
+ // dest == 0, so need to add 1 by hand (answer will be -1)
+ dest->dig[0] = 1;
+ dest->len = 1;
+ } else {
+ // dest > 0, so can use mpn_add to add 1
+ dest->len = mpn_add(dest->dig, dest->dig, dest->len, &round_up, 1);
+ }
}
}
}