From 15acb1fc7ca4706b8f5c4e11ddb93d5b62041147 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Thu, 5 Oct 2023 15:49:07 -0400
Subject: [PATCH] Add ADC and ADD.
---
.../Implementation/PerformImplementation.hpp | 92 +++++++++++++++++++
InstructionSets/x86/Status.hpp | 4 +
OSBindings/Mac/Clock SignalTests/8088Tests.mm | 2 +-
3 files changed, 97 insertions(+), 1 deletion(-)
diff --git a/InstructionSets/x86/Implementation/PerformImplementation.hpp b/InstructionSets/x86/Implementation/PerformImplementation.hpp
index dbe68bc5d..8d20ab5b2 100644
--- a/InstructionSets/x86/Implementation/PerformImplementation.hpp
+++ b/InstructionSets/x86/Implementation/PerformImplementation.hpp
@@ -9,10 +9,51 @@
#ifndef PerformImplementation_h
#define PerformImplementation_h
+#include "../../../Numeric/Carry.hpp"
+
namespace InstructionSet::x86 {
namespace Primitive {
+//
+// BEGIN TEMPORARY COPY AND PASTE SECTION.
+//
+// The following are largely excised from the M68k PerformImplementation.hpp; if there proves to be no
+// reason further to specialise them, there'll be a factoring out. In some cases I've tightened the documentation.
+//
+
+/// @returns An int of type @c IntT with only the most-significant bit set.
+template <typename IntT> constexpr IntT top_bit() {
+ static_assert(!std::numeric_limits<IntT>::is_signed);
+ constexpr IntT max = std::numeric_limits<IntT>::max();
+ return max - (max >> 1);
+}
+
+/// @returns The number of bits in @c IntT.
+template <typename IntT> constexpr int bit_size() {
+ return sizeof(IntT) * 8;
+}
+
+/// @returns An int with the top bit indicating whether overflow occurred during the calculation of
+/// • @c lhs + @c rhs (if @c is_add is true); or
+/// • @c lhs - @c rhs (if @c is_add is false)
+/// and the result was @c result. All other bits will be clear.
+template <bool is_add, typename IntT>
+IntT overflow(IntT lhs, IntT rhs, IntT result) {
+ const IntT output_changed = result ^ rhs;
+ const IntT input_differed = lhs ^ rhs;
+
+ if constexpr (is_add) {
+ return top_bit<IntT>() & output_changed & ~input_differed;
+ } else {
+ return top_bit<IntT>() & output_changed & input_differed;
+ }
+}
+
+//
+// END COPY AND PASTE SECTION.
+//
+
void aaa(CPU::RegisterPair16 &ax, Status &status) {
/*
IF ((AL AND 0FH) > 9) OR (AF = 1)
@@ -101,6 +142,42 @@ void aas(CPU::RegisterPair16 &ax, Status &status) {
ax.halves.low &= 0x0f;
}
+template <typename IntT>
+void adc(IntT &destination, IntT source, Status &status) {
+ /*
+ DEST ← DEST + SRC + CF;
+ */
+ /*
+ The OF, SF, ZF, AF, CF, and PF flags are set according to the result.
+ */
+ const IntT result = destination + source + status.carry_bit<IntT>();
+
+ status.carry = Numeric::carried_out<bit_size<IntT>() - 1>(destination, source, result);
+ status.auxiliary_carry = Numeric::carried_in<4>(destination, source, result);
+ status.sign = status.zero = status.parity = result;
+ status.overflow = overflow<true, IntT>(destination, source, result);
+
+ destination = result;
+}
+
+template <typename IntT>
+void add(IntT &destination, IntT source, Status &status) {
+ /*
+ DEST ← DEST + SRC;
+ */
+ /*
+ The OF, SF, ZF, AF, CF, and PF flags are set according to the result.
+ */
+ const IntT result = destination + source;
+
+ status.carry = Numeric::carried_out<bit_size<IntT>() - 1>(destination, source, result);
+ status.auxiliary_carry = Numeric::carried_in<4>(destination, source, result);
+ status.sign = status.zero = status.parity = result;
+ status.overflow = overflow<true, IntT>(destination, source, result);
+
+ destination = result;
+}
+
}
template <
@@ -119,6 +196,21 @@ template <
case Operation::AAD: Primitive::aad(destination, source.halves.low, status); break;
case Operation::AAM: Primitive::aam(destination, source.halves.low, status); break;
case Operation::AAS: Primitive::aas(destination, status); break;
+
+ case Operation::ADC:
+ static_assert(operation != Operation::ADC || data_size == DataSize::Byte || data_size == DataSize::Word);
+ switch(data_size) {
+ case DataSize::Byte: Primitive::adc(destination.halves.low, source.halves.low, status); break;
+ case DataSize::Word: Primitive::adc(destination.full, source.full, status); break;
+ }
+ break;
+ case Operation::ADD:
+ static_assert(operation != Operation::ADD || data_size == DataSize::Byte || data_size == DataSize::Word);
+ switch(data_size) {
+ case DataSize::Byte: Primitive::add(destination.halves.low, source.halves.low, status); break;
+ case DataSize::Word: Primitive::add(destination.full, source.full, status); break;
+ }
+ break;
}
(void)flow_controller;
diff --git a/InstructionSets/x86/Status.hpp b/InstructionSets/x86/Status.hpp
index 4c922ca6b..dbb9b4295 100644
--- a/InstructionSets/x86/Status.hpp
+++ b/InstructionSets/x86/Status.hpp
@@ -58,12 +58,16 @@ struct Status {
uint32_t carry;
uint32_t auxiliary_carry;
uint32_t sign;
+ uint32_t overflow;
// Zero => set; non-zero => unset.
uint32_t zero;
// Odd number of bits => set; even => unset.
uint32_t parity;
+
+ // Convenience getters.
+ template <typename IntT> IntT carry_bit() { return carry ? 1 : 0; }
};
}
diff --git a/OSBindings/Mac/Clock SignalTests/8088Tests.mm b/OSBindings/Mac/Clock SignalTests/8088Tests.mm
index ce5fa332a..bf5577be3 100644
--- a/OSBindings/Mac/Clock SignalTests/8088Tests.mm
+++ b/OSBindings/Mac/Clock SignalTests/8088Tests.mm
@@ -197,7 +197,7 @@ constexpr char TestSuiteHome[] = "/Users/tharte/Projects/ProcessorTests/8088/v1"
InstructionSet::x86::perform<
InstructionSet::x86::Model::i8086,
- InstructionSet::x86::Operation::AAD,
+ InstructionSet::x86::Operation::ADD,
InstructionSet::x86::DataSize::Byte
>(
dest,