From 61212c934125c613828ca8dc95fc55e26fa88100 Mon Sep 17 00:00:00 2001
From: wheremyfoodat <gponiris2004@gmail.com>
Date: Sat, 24 Sep 2022 03:11:36 +0300
Subject: [PATCH] [PICA] Implement mul

---
 include/PICA/shader.hpp              |  2 ++
 src/core/PICA/shader_interpreter.cpp | 22 ++++++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/include/PICA/shader.hpp b/include/PICA/shader.hpp
index 2978192e..e4101141 100644
--- a/include/PICA/shader.hpp
+++ b/include/PICA/shader.hpp
@@ -14,6 +14,7 @@ namespace ShaderOpcodes {
 	enum : u32 {
 		ADD = 0x00,
 		DP4 = 0x02,
+		MUL = 0x08,
 		MOV = 0x13,
 		END = 0x22
 	};
@@ -41,6 +42,7 @@ class PICAShader {
 	void add(u32 instruction);
 	void dp4(u32 instruction);
 	void mov(u32 instruction);
+	void mul(u32 instruction);
 
 	// src1, src2 and src3 have different negation & component swizzle bits in the operand descriptor
 	// https://problemkaputt.github.io/gbatek.htm#3dsgpushaderinstructionsetopcodesummary in the
diff --git a/src/core/PICA/shader_interpreter.cpp b/src/core/PICA/shader_interpreter.cpp
index 0aae6da6..c55cd6a1 100644
--- a/src/core/PICA/shader_interpreter.cpp
+++ b/src/core/PICA/shader_interpreter.cpp
@@ -12,6 +12,7 @@ void PICAShader::run() {
 			case ShaderOpcodes::DP4: dp4(instruction); break;
 			case ShaderOpcodes::END: return; // Stop running shader
 			case ShaderOpcodes::MOV: mov(instruction); break;
+			case ShaderOpcodes::MUL: mul(instruction); break;
 			default:Helpers::panic("Unimplemented PICA instruction %08X (Opcode = %02X)", instruction, opcode);
 		}
 	}
@@ -58,6 +59,27 @@ void PICAShader::add(u32 instruction) {
 	}
 }
 
+void PICAShader::mul(u32 instruction) {
+	const u32 operandDescriptor = operandDescriptors[instruction & 0x7f];
+	const u32 src1 = (instruction >> 12) & 0x7f;
+	const u32 src2 = (instruction >> 7) & 0x1f; // src2 coming first because PICA moment
+	const u32 idx = (instruction >> 19) & 3;
+	const u32 dest = (instruction >> 21) & 0x1f;
+
+	if (idx) Helpers::panic("[PICA] MUL: idx != 0");
+	vec4f srcVec1 = getSourceSwizzled<1>(src1, operandDescriptor);
+	vec4f srcVec2 = getSourceSwizzled<2>(src2, operandDescriptor);
+
+	vec4f& destVector = getDest(dest);
+
+	u32 componentMask = operandDescriptor & 0xf;
+	for (int i = 0; i < 4; i++) {
+		if (componentMask & (1 << i)) {
+			destVector[3 - i] = srcVec1[3 - i] * srcVec2[3 - 1];
+		}
+	}
+}
+
 void PICAShader::mov(u32 instruction) {
 	const u32 operandDescriptor = operandDescriptors[instruction & 0x7f];
 	const u32 src = (instruction >> 12) & 0x7f;