From: Chris Duncan <chris@zoso.dev>
Date: Thu, 9 Jan 2025 16:08:29 +0000 (-0800)
Subject: Apply non-branching logic to original WebGL pow shader.
X-Git-Url: https://zoso.dev/?a=commitdiff_plain;h=55e76167a47cf696dfc06eef7f5beea2a82ce528;p=libnemo.git

Apply non-branching logic to original WebGL pow shader.
---

diff --git a/src/lib/nano-pow/shaders/gl-fragment.ts b/src/lib/nano-pow/shaders/gl-fragment.ts
index c88974f..2179e16 100644
--- a/src/lib/nano-pow/shaders/gl-fragment.ts
+++ b/src/lib/nano-pow/shaders/gl-fragment.ts
@@ -72,6 +72,7 @@ const uint SIGMA82[192] = uint[192](
 
 // G mixing function
 void G (uint ix, uint iy, uint a, uint b, uint c, uint d) {
+	bool carry;
 	uint o0;
 	uint o1;
 	uint xor0;
@@ -80,18 +81,16 @@ void G (uint ix, uint iy, uint a, uint b, uint c, uint d) {
 	// a = a + b;
 	o0 = v[a] + v[b];
 	o1 = v[a+1u] + v[b+1u];
-	if (v[a] > 0xFFFFFFFFu - v[b]) {
-		o1 = o1 + 1u;
-	}
+	carry = o0 < v[a];
+	o1 = o1 + uint(mix(0.0, 1.0, float(carry)));
 	v[a] = o0;
 	v[a+1u] = o1;
 
 	// a = a + m[sigma[r][2*i+0]];
 	o0 = v[a] + m[ix];
 	o1 = v[a+1u] + m[ix+1u];
-	if (v[a] > 0xFFFFFFFFu - m[ix]) {
-		o1 = o1 + 1u;
-	}
+	carry = o0 < v[a];
+	o1 = o1 + uint(mix(0.0, 1.0, float(carry)));
 	v[a] = o0;
 	v[a+1u] = o1;
 
@@ -104,9 +103,8 @@ void G (uint ix, uint iy, uint a, uint b, uint c, uint d) {
 	// c = c + d;
 	o0 = v[c] + v[d];
 	o1 = v[c+1u] + v[d+1u];
-	if (v[c] > 0xFFFFFFFFu - v[d]) {
-		o1 = o1 + 1u;
-	}
+	carry = o0 < v[c];
+	o1 = o1 + uint(mix(0.0, 1.0, float(carry)));
 	v[c] = o0;
 	v[c+1u] = o1;
 
@@ -119,18 +117,16 @@ void G (uint ix, uint iy, uint a, uint b, uint c, uint d) {
 	// a = a + b;
 	o0 = v[a] + v[b];
 	o1 = v[a+1u] + v[b+1u];
-	if (v[a] > 0xFFFFFFFFu - v[b]) {
-		o1 = o1 + 1u;
-	}
+	carry = o0 < v[a];
+	o1 = o1 + uint(mix(0.0, 1.0, float(carry)));
 	v[a] = o0;
 	v[a+1u] = o1;
 
 	// a = a + m[sigma[r][2*i+1]];
 	o0 = v[a] + m[iy];
 	o1 = v[a+1u] + m[iy+1u];
-	if (v[a] > 0xFFFFFFFFu - m[iy]) {
-		o1 = o1 + 1u;
-	}
+	carry = o0 < v[a];
+	o1 = o1 + uint(mix(0.0, 1.0, float(carry)));
 	v[a] = o0;
 	v[a+1u] = o1;
 
@@ -143,9 +139,8 @@ void G (uint ix, uint iy, uint a, uint b, uint c, uint d) {
 	// c = c + d;
 	o0 = v[c] + v[d];
 	o1 = v[c+1u] + v[d+1u];
-	if (v[c] > 0xFFFFFFFFu - v[d]) {
-		o1 = o1 + 1u;
-	}
+	carry = o0 < v[c];
+	o1 = o1 + uint(mix(0.0, 1.0, float(carry)));
 	v[c] = o0;
 	v[c+1u] = o1;