From c0bc7b6e2d090554c9d940bc3614e089a688503a Mon Sep 17 00:00:00 2001 From: Mattias Andrée Date: Thu, 3 Mar 2016 10:33:29 +0100 Subject: Add zabs, zadd, zdiv, zmod, zmodmul, zmodpow, zneg, zpow, zsub, and the newly introduced zmodsqr MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Signed-off-by: Mattias Andrée --- src/zmodpow.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) create mode 100644 src/zmodpow.c (limited to 'src/zmodpow.c') diff --git a/src/zmodpow.c b/src/zmodpow.c new file mode 100644 index 0000000..42bed2f --- /dev/null +++ b/src/zmodpow.c @@ -0,0 +1,50 @@ +/* See LICENSE file for copyright and license details. */ +#include "internals" + +#include + +#define tb libzahl_tmp_pow_b +#define tc libzahl_tmp_pow_c +#define td libzahl_tmp_pow_d + + +void +zmodpow(z_t a, z_t b, z_t c, z_t d) +{ + size_t i, n; + + if (zsignum(c) <= 0) { + if (zzero(c)) { + if (zzero(b)) { + errno = EDOM; /* Indeterminate form: 0:th power of 0 */ + FAILURE_JUMP(); + } + zsetu(a, 1); + } else if (zzero(b) || zzero(d)) { + errno = EDOM; /* Undefined form: Division by 0 */ + FAILURE_JUMP(); + } else { + SET_SIGNUM(a, 0); + } + return; + } else if (zzero(d)) { + errno = EDOM; /* Undefined form: Division by 0 */ + FAILURE_JUMP(); + } else if (zzero(b)) { + SET_SIGNUM(a, 0); + return; + } + + n = zbits(c); + + zmod(tb, b, d); + zset(tc, c); + zset(td, d); + zsetu(a, 1); + + for (i = 0; i < n; i++) { + if (zbtest(tc, i)) + zmodmul(a, a, tb, td); + zmodsqr(tb, tb, td); + } +} -- cgit v1.2.3-70-g09d2