From 1c2e383d8e8df323b4cebb302869fc15599961a0 Mon Sep 17 00:00:00 2001
From: J08nY
Date: Sun, 8 Oct 2023 20:57:24 +0200
Subject: Add fixed-base multipliers with precomputation.

---
 pyecsca/codegen/templates/mult_precomp.c | 85 ++++++++++++++++++++++++++++++++
 1 file changed, 85 insertions(+)
 create mode 100644 pyecsca/codegen/templates/mult_precomp.c

(limited to 'pyecsca/codegen/templates/mult_precomp.c')

diff --git a/pyecsca/codegen/templates/mult_precomp.c b/pyecsca/codegen/templates/mult_precomp.c
new file mode 100644
index 0000000..cafa0a9
--- /dev/null
+++ b/pyecsca/codegen/templates/mult_precomp.c
@@ -0,0 +1,85 @@
+#include "mult.h"
+#include "point.h"
+
+void scalar_mult_ltr(int order_blen, point_t **points, bn_t *scalar, point_t *point, curve_t *curve) {
+    {%- if scalarmult.complete %}
+        int nbits = order_blen - 1;
+    {%- else %}
+        int nbits = bn_bit_length(scalar) - 1;
+    {%- endif %}
+
+    {%- if scalarmult.always %}
+		point_t *dummy = point_new();
+	{%- endif %}
+
+    for (int i = nbits; i >= 0; i--) {
+        if (bn_get_bit(scalar, i) == 1) {
+            point_accumulate(point, points[i], curve, point);
+        } else {
+        	{%- if scalarmult.always %}
+			    point_accumulate(point, points[i], curve, dummy);
+			{%- endif %}
+        }
+    }
+
+    {%- if scalarmult.always %}
+	    point_free(dummy);
+	{%- endif %}
+}
+
+void scalar_mult_rtl(int order_blen, point_t **points, bn_t *scalar, point_t *point, curve_t *curve) {
+    {%- if scalarmult.complete %}
+        int nbits = order_blen;
+    {%- else %}
+        int nbits = bn_bit_length(scalar);
+    {%- endif %}
+
+    {%- if scalarmult.always %}
+		point_t *dummy = point_new();
+	{%- endif %}
+
+    for (int i = 0; i < nbits; i++) {
+        if (bn_get_bit(scalar, i) == 1) {
+            point_accumulate(point, points[i], curve, point);
+        } else {
+            {%- if scalarmult.always %}
+			    point_accumulate(point, points[i], curve, dummy);
+			{%- endif %}
+        }
+    }
+
+    {%- if scalarmult.always %}
+	    point_free(dummy);
+	{%- endif %}
+}
+
+static void scalar_mult_inner(bn_t *scalar, point_t *point, curve_t *curve, point_t *out) {
+	point_t *q = point_copy(curve->neutral);
+	int order_blen = bn_bit_length(&curve->n);
+    point_t **points = malloc(sizeof(point_t *) * (order_blen + 1));
+
+    point_t *current = point_copy(point);
+    for (int i = 0; i < order_blen + 1; i++) {
+        points[i] = point_copy(current);
+        if (i != order_blen) {
+            point_dbl(current, curve, current);
+        }
+    }
+    point_free(current);
+
+    {%- if scalarmult.direction == ProcessingDirection.LTR %}
+        scalar_mult_ltr(order_blen, points, scalar, q, curve);
+    {%- else %}
+        scalar_mult_rtl(order_blen, points, scalar, q, curve);
+    {%- endif %}
+
+    {%- if "scl" in scalarmult.formulas %}
+    	point_scl(q, curve, q);
+    {%- endif %}
+    point_set(q, out);
+    for (int i = 0; i < order_blen + 1; i++) {
+        point_free(points[i]);
+    }
+    free(points);
+	point_free(q);
+}
\ No newline at end of file
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