initial commit

Author: brpratt

.devcontainer/Dockerfile

@@ -0,0 +1,51 @@
+FROM debian:11
+
+ARG PACKAGES="\
+    ca-certificates \
+    curl \
+    dasm \
+    file \
+    gcc \
+    gdb \
+    git \
+    lbzip2 \
+    less \
+    libc6-dev \
+    locales \
+    lsb-release \
+    make \
+    man \
+    manpages \
+    manpages-dev \
+    procps \
+    ssh \
+    sudo \
+    vim \
+    xz-utils"
+
+# Install system packages
+RUN apt-get update \
+    && export DEBIAN_FRONTEND=noninteractive \
+    && apt-get -y upgrade --no-install-recommends \
+    && apt-get -y install --no-install-recommends ${PACKAGES}
+
+# Update locales for en_US.UTF-8
+RUN sed -i -e 's/# en_US.UTF-8 UTF-8/en_US.UTF-8 UTF-8/' /etc/locale.gen && \
+    dpkg-reconfigure --frontend=noninteractive locales && \
+    update-locale LANG=en_US.UTF-8
+
+# Create user
+ARG USERNAME=coder
+ARG USER_UID=1000
+ARG USER_GID=$USER_UID
+RUN groupadd --gid ${USER_GID} ${USERNAME} \
+    && useradd -s /bin/bash --uid ${USER_UID} --gid ${USER_GID} -m ${USERNAME}
+
+# Give user sudo permissions
+RUN echo ${USERNAME} ALL=\(root\) NOPASSWD:ALL > /etc/sudoers.d/${USERNAME} \
+    && chmod 0440 /etc/sudoers.d/${USERNAME}
+
+# Switch to user and configure terminal
+USER $USERNAME
+ARG TERM=xterm-256color
+ENV TERM=${TERM}

.devcontainer/devcontainer.json

@@ -0,0 +1,25 @@
+// https://aka.ms/devcontainer.json
+{
+    "name": "nes",
+    "build": {
+        "dockerfile": "Dockerfile"
+    },
+    "extensions": [
+        "ms-vscode.cpptools"
+    ],
+    "settings": {
+        "[c]": {
+            "editor.tabSize": 4,
+            "editor.insertSpaces": true
+        }
+    },
+
+    // support ptrace-based debuggers
+    "runArgs": [ "--cap-add=SYS_PTRACE", "--security-opt", "seccomp=unconfined" ],
+
+    "mounts": [
+        "source=${localEnv:HOME}${localEnv:USERPROFILE}/.ssh,target=/home/coder/.ssh,type=bind,consistency=cached"
+    ],
+
+    "remoteUser": "coder"
+}

.gitignore

@@ -0,0 +1,4 @@
+bin/
+obj/
+*.swp
+*.swo

.vscode/c_cpp_properties.json

@@ -0,0 +1,15 @@
+{
+    "configurations": [
+        {
+            "name": "default",
+            "intelliSenseMode": "linux-gcc-x64",
+            "compilerPath": "/usr/bin/gcc",
+            "cStandard": "gnu17",
+            "cppStandard": "c++17",
+            "includePath": [
+                "src"
+            ]
+        }
+    ],
+    "version": 4
+}

Makefile

@@ -0,0 +1,48 @@
+.PHONY: example clean test
+
+CC := gcc
+CFLAGS := -Wall -Wextra -g
+
+example: bin/compy bin/program.bin
+	@./bin/compy ./bin/program.bin
+
+clean:
+	rm -rf obj/
+	rm -rf bin/
+
+obj/bus.o: src/bus.c src/bus.h
+	@mkdir -p obj
+	$(CC) $(CFLAGS) -c -o obj/bus.o $<
+
+obj/cpu.o: src/cpu.c src/cpu.h src/bus.h
+	@mkdir -p obj
+	$(CC) $(CFLAGS) -c -o obj/cpu.o $<
+
+obj/main.o: example/main.c src/bus.h src/cpu.h
+	@mkdir -p obj
+	$(CC) $(CFLAGS) -Isrc -c -o obj/main.o $<
+
+bin/compy: obj/bus.o obj/cpu.o obj/main.o
+	@mkdir -p bin
+	$(CC) $(CFLAGS) $^ -o bin/compy
+
+bin/program.bin: example/program.asm
+	@mkdir -p bin
+	dasm $< -f3 -obin/program.bin
+
+test: bin/bus_test bin/cpu_test bin/6502_functional_test
+	@./bin/bus_test
+	@./bin/cpu_test
+	@./bin/6502_functional_test
+
+bin/bus_test: test/test.c test/test.h test/bus_test.c obj/bus.o
+	@mkdir -p bin
+	$(CC) -o bin/bus_test $(CFLAGS) -Isrc $^
+
+bin/cpu_test: test/test.c test/test.h test/cpu_test.c obj/bus.o obj/cpu.o
+	@mkdir -p bin
+	$(CC) -o bin/cpu_test $(CLFAGS) -Isrc $^
+
+bin/6502_functional_test: test/test.c test/test.h test/6502_functional_test.c obj/bus.o obj/cpu.o
+	@mkdir -p bin
+	$(CC) -o bin/6502_functional_test $(CLFAGS) -Isrc $^

README.md

@@ -0,0 +1 @@
+# 6502

example/main.c

@@ -0,0 +1,94 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "bus.h"
+#include "cpu.h"
+
+const char * banner =
+"#################\n"
+"#     COMPY     #\n"
+"#################\n\n";
+
+static struct memory {
+    uint8_t ram[0x8000];
+    uint8_t rom[0x8000];
+} memory;
+
+static uint8_t peek(void *inst, uint16_t addr) {
+    struct memory *mem = (struct memory *)inst;
+
+    if (addr < 0x8000) {
+        return mem->ram[addr];
+    } else {
+        return mem->rom[addr - 0x8000];
+    }
+}
+
+static void poke(void *inst, uint16_t addr, uint8_t data) {
+    struct memory *mem = (struct memory *)inst;
+
+    if (addr < 0x8000) {
+        mem->ram[addr] = data;
+    }
+}
+
+static size_t load(FILE *bin) {
+    uint8_t binbuf[0x10000];
+
+    size_t bytes_read = fread(binbuf, 1, 0x10000, bin);
+
+    if (bytes_read < 0x8000) {
+        memcpy(memory.ram, binbuf, bytes_read);
+        return bytes_read;
+    }
+
+    memcpy(memory.ram, binbuf, 0x8000);
+    memcpy(memory.rom, binbuf + 0x8000, bytes_read - 0x8000);
+    return bytes_read;
+}
+
+int main(int argc, char *argv[]) {
+    struct bus bus = {
+        .inst = &memory,
+        .peek = peek,
+        .poke = poke
+    };
+
+    if (argc != 2) {
+        printf("Usage: compy <program>\n");
+        return 1;
+    }
+
+    FILE *bin = fopen(argv[1], "r");
+    if (bin == NULL) {
+        printf("ERROR: unable to open %s\n", argv[1]);
+        return 1;
+    }
+
+    size_t bytes_read = load(bin);
+    fclose(bin);
+
+    if (bytes_read != 0x10000) {
+        printf("ERROR: program file is not 0x10000 bytes\n");
+        return 1;
+    }
+
+    uint16_t pc_start = bus_peek(&bus, 0xFFFD);
+    pc_start = pc_start << 8 | bus_peek(&bus, 0xFFFC);
+
+    struct cpu cpu;
+    cpu_init(&cpu, pc_start);
+
+    printf(banner);
+
+    uint16_t prev_pc;
+    do {
+        prev_pc = cpu.pc;
+        cpu_step(&cpu, &bus);
+    } while (prev_pc != cpu.pc);
+
+    printf("Result of computation is: %d\n", memory.ram[0]);
+
+    return 0;
+}

example/program.asm

@@ -0,0 +1,17 @@
+    processor 6502
+
+    org $0000,0
+    ds $8000
+
+    org $8000
+start:
+    lda #1
+    adc #2
+    sta 0
+trap:
+    jmp trap
+
+    org $FFFA
+    dc.w start
+    dc.w start
+    dc.w start

src/bus.c

@@ -0,0 +1,11 @@
+#include <stdlib.h>
+
+#include "bus.h"
+
+uint8_t bus_peek(const struct bus *bus, uint16_t addr) {
+    return bus->peek(bus->inst, addr);
+}
+
+void bus_poke(const struct bus *bus, uint16_t addr, uint8_t data) {
+    bus->poke(bus->inst, addr, data);
+}

src/bus.h

@@ -0,0 +1,16 @@
+#ifndef __BUS_H__
+#define __BUS_H__
+
+#include <stdint.h>
+
+struct bus {
+    void *inst;
+    uint8_t (*peek)(void *inst, uint16_t addr);
+    void (*poke)(void *inst, uint16_t addr, uint8_t data);
+};
+
+
+uint8_t bus_peek(const struct bus *bus, uint16_t addr);
+void bus_poke(const struct bus *bus, uint16_t addr, uint8_t data);
+
+#endif