"mamelink", a replacement for Fastlink using a MAME plugin

.gitignore

@@ -0,0 +1,3 @@
+*.o
+down
+console_history

mamelink/Makefile

@@ -0,0 +1,3 @@
+all: mamelink.o down
+
+down: mamelink.o down.o

mamelink/down.c

@@ -0,0 +1,92 @@
+// A recreation of the "down" tool used by fred. Expects an object file
+// following the "slinky" object format, piped to stdin. 
+// https://github.com/ssalevan/habiclient/blob/master/Tools/slinky/link.c
+
+#include <assert.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <unistd.h>
+#include "mamelink.h"
+
+typedef unsigned char	byte;
+typedef unsigned short	word;
+
+byte buf[64 * 1024];
+
+size_t tryreadbytes(size_t count) {
+    size_t readcount = 0;
+    while (readcount < count) {
+        ssize_t result = read(STDIN_FILENO, buf + readcount, count);
+        readcount += result;
+        assert(result >= 0);
+        if (result == 0) {
+            break;
+        }
+    }
+    return readcount;
+}
+
+void readbytes(size_t count) {
+    assert(tryreadbytes(count));
+}
+
+word readword() {
+    readbytes(2);
+    return (unsigned short)buf[0] | ((unsigned short)buf[1] << 8);
+}
+
+bool tryreadword(word *val) {
+    if (tryreadbytes(2) != 2) {
+        return false;
+    } else {
+        *val = (unsigned short)buf[0] | ((unsigned short)buf[1] << 8);
+        return true;
+    }
+}
+
+word entryPoint = 0;
+
+void sendAbsoluteSegments() {
+    while (true) {
+        word start;
+        if (!tryreadword(&start) || start == 0xffff) {
+            break;
+        }
+        word end = readword();
+        assert(end >= start);
+
+        word count = end - start + 1;
+        readbytes(count);
+        printf("Segment: %4x-%4x\n", start, end);
+        down(buf, count, start);
+        if (start == end) {
+            entryPoint = start;
+        }
+    }
+}
+
+void sendRelocatableSegments() {
+    // hope Slinky has already pre-relocated all segments??
+    word start;
+    assert(!tryreadword(&start) || start == 0xffff);
+}
+
+int main(int argc, char *argv) {
+
+    Init(NULL);
+
+    // object starts with "magic" divider
+    assert(readword() == 0xffff);
+
+    sendAbsoluteSegments();
+    sendRelocatableSegments();
+
+    if (entryPoint != 0) {
+        printf("SYS%d\n", entryPoint);
+        JumpTo(entryPoint);
+    }
+
+    Finish();
+
+    return 0;
+}

mamelink/mamelink.c

@@ -0,0 +1,128 @@
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+static char* linkdir = NULL;
+
+#define MAMELINK_CONTINUE 0
+#define MAMELINK_PAUSE    1
+#define MAMELINK_LOAD     2
+#define MAMELINK_STORE    3
+#define MAMELINK_JUMP     4
+
+static int prepare_cmd(char command) {
+    assert(linkdir != NULL);
+
+    const char *pendingfilename = "/linkin.pending";
+    char path[strlen(linkdir) + strlen(pendingfilename) + 1];
+    int fd = -1;
+
+    sprintf(path, "%s%s", linkdir, pendingfilename);
+    while (fd < 0) {
+        fd = open(path, O_CREAT | O_EXCL | O_WRONLY, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP);
+        if (fd < 0) { 
+            assert(errno == EEXIST);
+            usleep(100);
+        }
+    }
+
+    write(fd, &command, 1);
+    return fd;
+}
+
+static int send_cmd(int cmd_fd) {
+    assert(linkdir != NULL);
+
+    const char *pendingfilename = "/linkin.pending";
+    const char *infilename = "/linkin";
+    const char *outfilename = "/linkout";
+    char path[strlen(linkdir) + strlen(pendingfilename) + 1];
+    char finalpath[strlen(linkdir) + strlen(infilename) + 1];
+    
+    sprintf(path, "%s%s", linkdir, pendingfilename);
+    sprintf(finalpath, "%s%s", linkdir, infilename);
+
+    rename(path, finalpath);
+
+    // the plugin will delete linkin once it has completed processing
+    while (access(finalpath, F_OK) == 0) {
+        usleep(100);
+    }
+    sprintf(path, "%s%s", linkdir, outfilename);
+    int fd = open(path, O_RDONLY);
+    assert(fd >= 0);
+    return fd;
+}
+
+static void close_response(int response_fd) {
+    assert(linkdir != NULL);
+
+    const char *outfilename = "/linkout";
+    char path[strlen(linkdir) + strlen(outfilename) + 1];
+
+    sprintf(path, "%s%s", linkdir, outfilename);
+    unlink(path);
+    close(response_fd);
+}
+
+static void send_cmd_and_close(int cmd_fd) {
+    close_response(send_cmd(cmd_fd));
+}
+
+static void simple_cmd(char command) {
+    send_cmd_and_close(prepare_cmd(command));
+}
+
+void Init(char *initial_link_dir) {
+    if (initial_link_dir == NULL) {
+        initial_link_dir = getenv("MAMELINK");
+    }
+    assert(initial_link_dir != NULL);
+    if (linkdir != NULL) {
+        free(linkdir);
+    }
+    linkdir = strdup(initial_link_dir);
+}
+
+void Finish() {
+    if (linkdir != NULL) {
+        free(linkdir);
+        linkdir = NULL;
+    }
+}
+
+static int write_word(int fd, unsigned short val) {
+    const char buf[2] = { val & 0xff, (val >> 8) & 0xff };
+    return write(fd, buf, 2);
+}
+
+void down(char *buf, unsigned short bytes, unsigned short c64Addr) {
+    int cmd_fd = prepare_cmd(MAMELINK_STORE);
+    write_word(cmd_fd, c64Addr);
+    write_word(cmd_fd, bytes);
+    write(cmd_fd, buf, bytes);
+    send_cmd_and_close(cmd_fd);
+}
+
+void up(char *buf, unsigned short bytes, unsigned short c64Addr) {
+    int fd = prepare_cmd(MAMELINK_STORE);
+    write_word(fd, c64Addr);
+    write_word(fd, bytes);
+    fd = send_cmd(fd);
+    read(fd, buf, bytes);
+    close_response(fd);
+}
+
+void Cont() {
+    simple_cmd(MAMELINK_CONTINUE);
+}
+
+void JumpTo(unsigned short c64Addr) {
+    int fd = prepare_cmd(MAMELINK_JUMP);
+    write_word(fd, c64Addr);
+    send_cmd_and_close(fd);
+}

mamelink/mamelink.h

@@ -0,0 +1,6 @@
+void Init(char *initial_link_dir);
+void Finish();
+void down(char *buf, unsigned short bytes, unsigned short c64Addr);
+void up(char *buf, unsigned short bytes, unsigned short c64Addr);
+void Cont();
+void JumpTo(unsigned short c64Addr);

mamelink/mameplugins/mamelink/init.lua

@@ -0,0 +1,98 @@
+-- license:MIT
+-- copyright-holders: Jeremy Penner
+local exports = {
+	name = "mamelink",
+	version = "0.0.1",
+	description = "Socket-based recreation of Lucasfilm's Fastlink interface",
+	license = "MIT",
+	author = { name = "Jeremy Penner" } 
+}
+
+local function readword(bytein)
+    local lo = bytein()
+    local hi = bytein()
+    return lo | (hi << 8)
+end
+
+local function fastlink(bytein, byteout)
+    print("starting fastlink")
+    while true do
+        local command = bytein()
+        local cpu = manager.machine.devices[":u7"]
+        local mem = cpu.spaces.program
+        print("Got command", command)
+        if command == 0 then -- continue
+            manager.machine.debugger:command("go")
+        elseif command == 1 then -- pause
+            manager.machine.debugger:command("step")
+        elseif command == 2 then -- load bytes
+            local address = readword(bytein)
+            local length = readword(bytein)
+            for i = 1, length do
+                byteout(mem:read_u8(address + i - 1))
+            end
+        elseif command == 3 then -- store bytes
+            local address = readword(bytein)
+            local length = readword(bytein)
+            for i = 1, length do
+                mem:write_u8(address + i - 1, bytein())
+            end
+        elseif command == 4 then -- jump
+            local address = readword(bytein)
+            cpu.state["PC"].value = address
+        else 
+            print("Unknown command: " .. tostring(command))
+        end
+    end
+end
+
+local function is_booted()
+    local cpu = manager.machine.devices[":u7"]
+    local mem = cpu.spaces.program
+    return mem
+end
+
+function exports.startplugin()
+    local infilename = manager.plugins["mamelink"].directory .. "/linkin"
+    local outfilename = manager.plugins["mamelink"].directory .. "/linkout"
+    local pendingfilename = outfilename .. ".pending"
+
+    local link = coroutine.create(fastlink)
+
+    local linkio = {}
+    local function bytein()
+        while true do
+            local data = nil
+            if linkio.infile then
+                data = linkio.infile:read(1)
+            end
+            if data then
+                return string.byte(data)
+            else
+                coroutine.yield()
+            end
+        end
+    end
+    local function byteout(byte)
+        io.outfile:write(string.char(byte))
+    end
+
+    print(coroutine.resume(link, bytein, byteout))
+
+    emu.register_periodic(function()
+        if not is_booted() then return end
+        linkio.infile = io.open(infilename, "rb")
+        if linkio.infile then
+            linkio.outfile = io.open(pendingfilename, "wb")
+            print(coroutine.resume(link))
+            linkio.infile:close()
+            linkio.infile = nil
+            linkio.outfile:close()
+            linkio.outfile = nil
+            os.rename(pendingfilename, outfilename)
+            os.remove(infilename)
+        end
+    end)
+end
+
+return exports

mamelink/mameplugins/mamelink/plugin.json

@@ -0,0 +1,10 @@
+{
+  "plugin": {
+	"name": "mamelink",
+	"description": "Socket-based recreation of Lucasfilm's Fastlink interface",
+	"version": "0.0.1",
+	"author": "Jeremy Penner",
+	"type": "plugin",
+	"start": "false"
+  }
+}

mamelink/reno.sh

@@ -0,0 +1,4 @@
+#!/usr/bin/env bash
+SCRIPTPATH="$( cd -- "$(dirname "${BASH_SOURCE[0]}")" >/dev/null 2>&1 ; pwd -P )"
+export MAMELINK="${SCRIPTPATH}/mameplugins/mamelink"
+./down < reno.out

mamelink/start

@@ -0,0 +1,6 @@
+#!/usr/bin/env bash
+SCRIPTPATH="$( cd -- "$(dirname "${BASH_SOURCE[0]}")" >/dev/null 2>&1 ; pwd -P )"
+pluginspath="$(mame -showconfig | grep pluginspath | sed 's/^pluginspath \+//g')"
+mame c64 -window -plugins -pluginspath "${pluginspath};${SCRIPTPATH}/mameplugins" -plugin mamelink &
+export MAMELINK="${SCRIPTPATH}/mameplugins/mamelink"
+./down < reno.out