65816-llvm-mos/src/link816/omfEmit.cpp
Scott Duensing 6d7eae0356 Checkpoint.
2026-04-30 01:29:16 -05:00

201 lines
7.3 KiB
C++

// omfEmit — wrap a flat binary in a minimal Apple IIgs OMF v2.1
// container so GS/OS can load and execute it.
//
// Single-segment output (CODE, kind=0), no INTERSEG opcodes (multi-
// segment output is a follow-on). Header layout per OMF 2.1 spec:
// 44-byte fixed header + 10-byte LOAD_NAME + 32-byte SEG_NAME, then
// the body (DS opcode for the payload, END opcode terminator).
//
// CLI mirrors the Python tool exactly:
// omfEmit --input flat.bin --map flat.map --base 0x8000
// --entry main --output prog.omf [--name SEG]
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <fstream>
#include <map>
#include <string>
#include <vector>
namespace {
[[noreturn]] static void die(const std::string &msg) {
std::fprintf(stderr, "omfEmit: %s\n", msg.c_str());
std::exit(1);
}
static std::vector<uint8_t> readFile(const std::string &path) {
std::ifstream f(path, std::ios::binary);
if (!f) die("cannot open '" + path + "' for reading");
return std::vector<uint8_t>((std::istreambuf_iterator<char>(f)),
std::istreambuf_iterator<char>());
}
static std::map<std::string, uint32_t> readMap(const std::string &path) {
std::map<std::string, uint32_t> syms;
std::ifstream f(path);
if (!f) die("cannot open '" + path + "' for reading");
std::string line;
while (std::getline(f, line)) {
auto eq = line.find(" = ");
if (eq == std::string::npos) continue;
std::string name = line.substr(0, eq);
std::string addr = line.substr(eq + 3);
// Trim trailing whitespace.
while (!name.empty() && std::isspace((unsigned char)name.back()))
name.pop_back();
while (!addr.empty() && std::isspace((unsigned char)addr.back()))
addr.pop_back();
try {
syms[name] = std::stoul(addr, nullptr, 16);
} catch (...) { /* skip non-hex entries */ }
}
return syms;
}
// Emit little-endian.
static void put32(std::vector<uint8_t> &v, uint32_t x) {
v.push_back(x & 0xFF);
v.push_back((x >> 8) & 0xFF);
v.push_back((x >> 16) & 0xFF);
v.push_back((x >> 24) & 0xFF);
}
static void put16(std::vector<uint8_t> &v, uint16_t x) {
v.push_back(x & 0xFF);
v.push_back((x >> 8) & 0xFF);
}
static std::vector<uint8_t> emitOMF(const std::vector<uint8_t> &image,
uint32_t entryOffset,
const std::string &name) {
// Body: DS (literal data) + END.
std::vector<uint8_t> body;
if (!image.empty()) {
body.push_back(0xF1); // DS opcode
put32(body, static_cast<uint32_t>(image.size()));
body.insert(body.end(), image.begin(), image.end());
}
body.push_back(0x00); // END opcode
// LOAD_NAME: 10 bytes, space-padded.
std::string loadName = name.substr(0, 10);
while (loadName.size() < 10) loadName += ' ';
// SEG_NAME: 1-byte length prefix + 31 bytes (truncated, padded with NUL).
std::string segNameTxt = name.substr(0, 31);
std::vector<uint8_t> segName;
segName.push_back(static_cast<uint8_t>(segNameTxt.size()));
for (char c : segNameTxt) segName.push_back((uint8_t)c);
while (segName.size() < 32) segName.push_back(0);
constexpr uint16_t DISPNAME = 44;
const uint16_t DISPDATA = DISPNAME + 10 + 32;
const uint32_t LENGTH = static_cast<uint32_t>(image.size());
const uint32_t BYTECNT = DISPDATA + static_cast<uint32_t>(body.size());
const uint32_t RESSPC = 0;
const uint32_t BANKSIZE = 0x10000;
const uint16_t KIND = 0x0000; // CODE
const uint32_t ORG = 0;
const uint32_t ALIGN = 0;
const uint8_t NUMSEX = 0;
const uint16_t SEGNUM = 1;
const uint32_t ENTRY = entryOffset;
std::vector<uint8_t> hdr;
put32(hdr, BYTECNT);
put32(hdr, RESSPC);
put32(hdr, LENGTH);
hdr.push_back(0x00); // undefined
hdr.push_back(10); // LABLEN
hdr.push_back(4); // NUMLEN
hdr.push_back(0x21); // VERSION 2.1
put32(hdr, BANKSIZE);
put16(hdr, KIND);
hdr.push_back(0x00); hdr.push_back(0x00); // undefined (2 bytes)
put32(hdr, ORG);
put32(hdr, ALIGN);
hdr.push_back(NUMSEX);
hdr.push_back(0x00); // undefined
put16(hdr, SEGNUM);
put32(hdr, ENTRY);
put16(hdr, DISPNAME);
put16(hdr, DISPDATA);
if (hdr.size() != 44) die("internal: header size != 44");
std::vector<uint8_t> out;
out.insert(out.end(), hdr.begin(), hdr.end());
out.insert(out.end(), loadName.begin(), loadName.end());
out.insert(out.end(), segName.begin(), segName.end());
out.insert(out.end(), body.begin(), body.end());
return out;
}
static uint32_t parseInt(const std::string &s) {
return static_cast<uint32_t>(std::stoul(s, nullptr, 0));
}
static void usage(const char *argv0) {
std::fprintf(stderr,
"usage: %s --input FLAT --map FILE --base ADDR --entry SYM\n"
" --output OMF [--name NAME]\n",
argv0);
std::exit(2);
}
} // namespace
int main(int argc, char **argv) {
std::string input, mapFile, output, entry = "main", name;
uint32_t base = 0;
bool baseSet = false;
int i = 1;
while (i < argc) {
std::string a = argv[i];
if (a == "--input") { if (++i >= argc) usage(argv[0]); input = argv[i++]; }
else if (a == "--map") { if (++i >= argc) usage(argv[0]); mapFile = argv[i++]; }
else if (a == "--base") { if (++i >= argc) usage(argv[0]); base = parseInt(argv[i++]); baseSet = true; }
else if (a == "--entry") { if (++i >= argc) usage(argv[0]); entry = argv[i++]; }
else if (a == "--name") { if (++i >= argc) usage(argv[0]); name = argv[i++]; }
else if (a == "--output" || a == "-o") { if (++i >= argc) usage(argv[0]); output = argv[i++]; }
else if (a == "-h" || a == "--help") usage(argv[0]);
else die("unknown option '" + a + "'");
}
if (input.empty() || mapFile.empty() || !baseSet || output.empty())
usage(argv[0]);
auto image = readFile(input);
auto syms = readMap(mapFile);
auto it = syms.find(entry);
if (it == syms.end())
die("entry symbol '" + entry + "' not in map");
uint32_t entryAddr = it->second;
if (entryAddr < base || entryAddr >= base + image.size())
die("entry symbol outside linked image");
uint32_t entryOff = entryAddr - base;
if (name.empty()) {
// Default name: output basename without extension.
size_t slash = output.find_last_of('/');
std::string base_n = (slash == std::string::npos) ? output
: output.substr(slash + 1);
size_t dot = base_n.find_last_of('.');
name = (dot == std::string::npos) ? base_n : base_n.substr(0, dot);
}
auto blob = emitOMF(image, entryOff, name);
std::ofstream f(output, std::ios::binary);
if (!f) die("cannot open '" + output + "' for writing");
f.write(reinterpret_cast<const char *>(blob.data()), blob.size());
std::fprintf(stderr,
"OMF: 1 segment, %zu bytes payload, entry='%s' at +0x%x -> %s "
"(%zu bytes total)\n",
image.size(), entry.c_str(), entryOff,
output.c_str(), blob.size());
return 0;
}