--- /dev/null
+/* TomsFastMath, a fast ISO C bignum library.
+ *
+ * This project is meant to fill in where LibTomMath
+ * falls short. That is speed ;-)
+ *
+ * This project is public domain and free for all purposes.
+ *
+ * Tom St Denis, tomstdenis@gmail.com
+ */
+#include <tfm_private.h>
+
+static int s_is_power_of_two(fp_digit b, int *p)
+{
+ int x;
+
+ /* fast return if no power of two */
+ if ((b==0) || (b & (b-1))) {
+ return 0;
+ }
+
+ for (x = 0; x < DIGIT_BIT; x++) {
+ if (b == (((fp_digit)1)<<x)) {
+ *p = x;
+ return 1;
+ }
+ }
+ return 0;
+}
+
+/* a/b => cb + d == a */
+int fp_div_d(fp_int *a, fp_digit b, fp_int *c, fp_digit *d)
+{
+ fp_int q;
+ fp_word w;
+ fp_digit t;
+ int ix;
+
+ /* cannot divide by zero */
+ if (b == 0) {
+ return FP_VAL;
+ }
+
+ /* quick outs */
+ if (b == 1 || fp_iszero(a) == 1) {
+ if (d != NULL) {
+ *d = 0;
+ }
+ if (c != NULL) {
+ fp_copy(a, c);
+ }
+ return FP_OKAY;
+ }
+
+ /* power of two ? */
+ if (s_is_power_of_two(b, &ix) == 1) {
+ if (d != NULL) {
+ *d = a->dp[0] & ((((fp_digit)1)<<ix) - 1);
+ }
+ if (c != NULL) {
+ fp_div_2d(a, ix, c, NULL);
+ }
+ return FP_OKAY;
+ }
+
+ /* no easy answer [c'est la vie]. Just division */
+ fp_init(&q);
+
+ q.used = a->used;
+ q.sign = a->sign;
+ w = 0;
+ for (ix = a->used - 1; ix >= 0; ix--) {
+ w = (w << ((fp_word)DIGIT_BIT)) | ((fp_word)a->dp[ix]);
+
+ if (w >= b) {
+ t = (fp_digit)(w / b);
+ w -= ((fp_word)t) * ((fp_word)b);
+ } else {
+ t = 0;
+ }
+ q.dp[ix] = (fp_digit)t;
+ }
+
+ if (d != NULL) {
+ *d = (fp_digit)w;
+ }
+
+ if (c != NULL) {
+ fp_clamp(&q);
+ fp_copy(&q, c);
+ }
+
+ return FP_OKAY;
+}
+
+
+/* $Source$ */
+/* $Revision$ */
+/* $Date$ */