inhabitor/mamelink/down.c

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// 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 == 0) {
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;
}