3 files changed, 104 insertions, 12 deletions

diff --git a/src/shader_recompiler/CMakeLists.txt b/src/shader_recompiler/CMakeLists.txt
index 981a79e44..8a0f73a4d 100644
--- a/src/shader_recompiler/CMakeLists.txt
+++ b/src/shader_recompiler/CMakeLists.txt
@@ -74,6 +74,7 @@ add_library(shader_recompiler STATIC
     frontend/maxwell/translate/impl/impl.cpp
     frontend/maxwell/translate/impl/impl.h
     frontend/maxwell/translate/impl/integer_add.cpp
+    frontend/maxwell/translate/impl/integer_add_three_input.cpp
     frontend/maxwell/translate/impl/integer_compare.cpp
     frontend/maxwell/translate/impl/integer_compare_and_set.cpp
     frontend/maxwell/translate/impl/integer_minimum_maximum.cpp
diff --git a/src/shader_recompiler/frontend/maxwell/translate/impl/integer_add_three_input.cpp b/src/shader_recompiler/frontend/maxwell/translate/impl/integer_add_three_input.cpp
new file mode 100644
index 000000000..c2dbd7998
--- /dev/null
+++ b/src/shader_recompiler/frontend/maxwell/translate/impl/integer_add_three_input.cpp
@@ -0,0 +1,103 @@
+// Copyright 2021 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include "common/bit_field.h"
+#include "common/common_types.h"
+#include "shader_recompiler/frontend/maxwell/translate/impl/impl.h"
+
+namespace Shader::Maxwell {
+namespace {
+enum class Shift : u64 {
+    None,
+    Right,
+    Left,
+};
+enum class Half : u64 {
+    All,
+    Lower,
+    Upper,
+};
+
+[[nodiscard]] IR::U32 IntegerHalf(IR::IREmitter& ir, const IR::U32& value, Half half) {
+    constexpr bool is_signed{false};
+    switch (half) {
+    case Half::Lower:
+        return ir.BitFieldExtract(value, ir.Imm32(0), ir.Imm32(16), is_signed);
+    case Half::Upper:
+        return ir.BitFieldExtract(value, ir.Imm32(16), ir.Imm32(16), is_signed);
+    default:
+        return value;
+    }
+}
+
+[[nodiscard]] IR::U32 IntegerShift(IR::IREmitter& ir, const IR::U32& value, Shift shift) {
+    switch (shift) {
+    case Shift::Right:
+        return ir.ShiftRightLogical(value, ir.Imm32(16));
+    case Shift::Left:
+        return ir.ShiftLeftLogical(value, ir.Imm32(16));
+    default:
+        return value;
+    }
+}
+
+void IADD3(TranslatorVisitor& v, u64 insn, IR::U32 op_b, IR::U32 op_c) {
+    union {
+        u64 insn;
+        BitField<0, 8, IR::Reg> dest_reg;
+        BitField<8, 8, IR::Reg> src_a;
+        BitField<31, 2, Half> half_c;
+        BitField<33, 2, Half> half_b;
+        BitField<35, 2, Half> half_a;
+        BitField<37, 2, Shift> shift;
+        BitField<47, 1, u64> cc;
+        BitField<48, 1, u64> x;
+        BitField<49, 1, u64> neg_c;
+        BitField<50, 1, u64> neg_b;
+        BitField<51, 1, u64> neg_a;
+    } iadd3{insn};
+
+    if (iadd3.x != 0) {
+        throw NotImplementedException("IADD3 X");
+    }
+    if (iadd3.cc != 0) {
+        throw NotImplementedException("IADD3 CC");
+    }
+
+    IR::U32 op_a{v.X(iadd3.src_a)};
+    op_a = IntegerHalf(v.ir, op_a, iadd3.half_a);
+    op_b = IntegerHalf(v.ir, op_b, iadd3.half_b);
+    op_c = IntegerHalf(v.ir, op_c, iadd3.half_c);
+
+    if (iadd3.neg_a != 0) {
+        op_a = v.ir.INeg(op_a);
+    }
+    if (iadd3.neg_b != 0) {
+        op_b = v.ir.INeg(op_b);
+    }
+    if (iadd3.neg_c != 0) {
+        op_c = v.ir.INeg(op_c);
+    }
+
+    IR::U32 lhs{v.ir.IAdd(op_a, op_b)};
+    lhs = IntegerShift(v.ir, lhs, iadd3.shift);
+    const IR::U32 result{v.ir.IAdd(lhs, op_c)};
+
+    v.X(iadd3.dest_reg, result);
+}
+} // Anonymous namespace
+
+void TranslatorVisitor::IADD3_reg(u64 insn) {
+    IADD3(*this, insn, GetReg20(insn), GetReg39(insn));
+}
+
+void TranslatorVisitor::IADD3_cbuf(u64 insn) {
+    IADD3(*this, insn, GetCbuf(insn), GetReg39(insn));
+}
+
+void TranslatorVisitor::IADD3_imm(u64 insn) {
+    IADD3(*this, insn, GetImm20(insn), GetReg39(insn));
+}
+
+} // namespace Shader::Maxwell
diff --git a/src/shader_recompiler/frontend/maxwell/translate/impl/not_implemented.cpp b/src/shader_recompiler/frontend/maxwell/translate/impl/not_implemented.cpp
index 91a9858c6..c93304a67 100644
--- a/src/shader_recompiler/frontend/maxwell/translate/impl/not_implemented.cpp
+++ b/src/shader_recompiler/frontend/maxwell/translate/impl/not_implemented.cpp
@@ -365,18 +365,6 @@ void TranslatorVisitor::I2I_imm(u64) {
     ThrowNotImplemented(Opcode::I2I_imm);
 }
 
-void TranslatorVisitor::IADD3_reg(u64) {
-    ThrowNotImplemented(Opcode::IADD3_reg);
-}
-
-void TranslatorVisitor::IADD3_cbuf(u64) {
-    ThrowNotImplemented(Opcode::IADD3_cbuf);
-}
-
-void TranslatorVisitor::IADD3_imm(u64) {
-    ThrowNotImplemented(Opcode::IADD3_imm);
-}
-
 void TranslatorVisitor::IDE(u64) {
     ThrowNotImplemented(Opcode::IDE);
 }