First commit

Signed-off-by: Mattias Andrée <m@maandree.se>

1 files changed, 34 insertions, 0 deletions

diff --git a/libquanta_bigint_divmod_small__.c b/libquanta_bigint_divmod_small__.c
new file mode 100644
index 0000000..a2c345f
--- /dev/null
+++ b/libquanta_bigint_divmod_small__.c
@@ -0,0 +1,34 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+
+uintmax_t
+libquanta_bigint_divmod_small__(struct bigint *big, uintmax_t small)
+{
+	uintmax_t q = 0, hi, lo;
+	int e = 8 * (int)sizeof(small);
+
+#if 0 /* this would overflow (undefined behaviour) and not fit in the result */
+	q = big->high / small;
+	q <<= 8 * (int)sizeof(small);
+#endif
+	big->high %= small;
+
+	while (big->high && --e) {
+		hi = small >> (8 * (int)sizeof(small) - e);
+		lo = small << e;
+
+		if (hi > big->high)
+			continue;
+		if (hi == big->high && lo > big->low)
+			continue;
+
+		q |= (uintmax_t)1 << e;
+		bigint_sub_small(big, lo);
+		big->high -= hi;
+	}
+
+	q += big->low / small;
+	big->low %= small;
+	return q;
+}