initial commit

1 files changed, 77 insertions, 0 deletions

diff --git a/third_party/bearssl/src/i32_decmod.c b/third_party/bearssl/src/i32_decmod.c
new file mode 100644
index 0000000..a859af1
--- /dev/null
+++ b/third_party/bearssl/src/i32_decmod.c
@@ -0,0 +1,77 @@
+/*
+ * Copyright (c) 2016 Thomas Pornin <[email protected]>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining 
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be 
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include "inner.h"
+
+/* see inner.h */
+uint32_t
+br_i32_decode_mod(uint32_t *x, const void *src, size_t len, const uint32_t *m)
+{
+	const unsigned char *buf;
+	uint32_t r;
+	size_t u, v, mlen;
+
+	buf = src;
+
+	/*
+	 * First pass: determine whether the value fits. The 'r' value
+	 * will contain the comparison result, as 0x00000000 (value is
+	 * equal to the modulus), 0x00000001 (value is greater than the
+	 * modulus), or 0xFFFFFFFF (value is lower than the modulus).
+	 */
+	mlen = (m[0] + 7) >> 3;
+	r = 0;
+	for (u = (mlen > len) ? mlen : len; u > 0; u --) {
+		uint32_t mb, xb;
+
+		v = u - 1;
+		if (v >= mlen) {
+			mb = 0;
+		} else {
+			mb = (m[1 + (v >> 2)] >> ((v & 3) << 3)) & 0xFF;
+		}
+		if (v >= len) {
+			xb = 0;
+		} else {
+			xb = buf[len - u];
+		}
+		r = MUX(EQ(r, 0), (uint32_t)CMP(xb, mb), r);
+	}
+
+	/*
+	 * Only r == 0xFFFFFFFF is acceptable. We want to set r to 0xFF if
+	 * the value fits, 0x00 otherwise.
+	 */
+	r >>= 24;
+	br_i32_zero(x, m[0]);
+	u = (mlen > len) ? len : mlen;
+	while (u > 0) {
+		uint32_t xb;
+
+		xb = buf[len - u] & r;
+		u --;
+		x[1 + (u >> 2)] |= xb << ((u & 3) << 3);
+	}
+	return r >> 7;
+}