Adding c model for the modexp core.

1 files changed, 93 insertions, 0 deletions

diff --git a/src/model/c/src/bignum_uint32_t.c b/src/model/c/src/bignum_uint32_t.c
new file mode 100644
index 0000000..75d27a8
--- /dev/null
+++ b/src/model/c/src/bignum_uint32_t.c
@@ -0,0 +1,93 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "bignum_uint32_t.h"
+
+void copy_array(int length, uint32_t *src, uint32_t *dst) {
+	for (int i = 0; i < length; i++)
+		dst[i] = src[i];
+}
+
+void add_array(int length, uint32_t *a, uint32_t *b, uint32_t *result) {
+	uint64_t carry = 0;
+	for (int i = length - 1; i >= 0; i--) {
+		uint64_t r = carry;
+		uint32_t aa = a[i];
+		uint32_t bb = b[i];
+		r += aa & 0xFFFFFFFFul;
+		r += bb & 0xFFFFFFFFul;
+		carry = r >> 32;
+		result[i] = (uint32_t) r;
+	}
+}
+
+void sub_array(int length, uint32_t *a, uint32_t *b, uint32_t *result) {
+	uint64_t carry = 1;
+	for (int wordIndex = length - 1; wordIndex >= 0; wordIndex--) {
+		uint64_t r = carry;
+		uint32_t aa = a[wordIndex];
+		uint32_t bb = ~b[wordIndex];
+		r += aa & 0xFFFFFFFFul;
+		r += bb & 0xFFFFFFFFul;
+		carry = r >> 32;
+		result[wordIndex] = (uint32_t) r;
+	}
+}
+
+void shift_right_1_array(int length, uint32_t *a, uint32_t *result) {
+	uint32_t prev = 0; // MSB will be zero extended
+	for (int wordIndex = 0; wordIndex < length; wordIndex++) {
+		uint32_t aa = a[wordIndex];
+		result[wordIndex] = (aa >> 1) | (prev << 31);
+		prev = aa & 1; // Lower word will be extended with LSB of this word
+	}
+}
+
+void shift_left_1_array(int length, uint32_t *a, uint32_t *result) {
+	uint32_t prev = 0; // LSB will be zero extended
+	for (int wordIndex = length - 1; wordIndex >= 0; wordIndex--) {
+		uint32_t aa = a[wordIndex];
+		result[wordIndex] = (aa << 1) | prev;
+
+		// Higher word will be extended with MSB of this word
+		prev = aa >> 31;
+	}
+}
+
+void debugArray(char *msg, int length, uint32_t *array) {
+	printf("%s ", msg);
+	for (int i = 0; i < length; i++) {
+		printf("%8x ", array[i]);
+	}
+	printf("\n");
+}
+
+void modulus_array(int length, uint32_t *a, uint32_t *modulus, uint32_t *temp,
+		uint32_t *reminder) {
+	copy_array(length, a, reminder);
+
+	while (!greater_than_array(length, modulus, reminder)) {
+
+		copy_array(length, modulus, temp);
+
+		while (((temp[0] & 0x80000000) == 0)
+				&& (!greater_than_array(length, temp, reminder))) {
+			sub_array(length, reminder, temp, reminder);
+			shift_left_1_array(length, temp, temp);
+		}
+	}
+}
+
+void zero_array(int length, uint32_t *a) {
+	for (int i = 0; i < length; i++)
+		a[i] = 0;
+}
+
+int greater_than_array(int length, uint32_t *a, uint32_t *b) {
+	for (int i = 0; i < length; i++) {
+		if (a[i] > b[i])
+			return 1;
+		if (a[i] < b[i])
+			return 0;
+	}
+	return 0;
+}