collapseos/tools/emul/zasm/zasm.c
Virgil Dupras af2c561c6b zasm: begin erroring out reliably
Up until now, invalid source input had undefined behavior. We're now
beginning to define that behavior so that zasm can be a bit more usable.
2019-05-27 11:04:31 -04:00

198 lines
4.8 KiB
C

#include <stdint.h>
#include <stdio.h>
#include "../libz80/z80.h"
#include "kernel.h"
#include "user.h"
#include "includes.h"
/* zasm reads from a specified blkdev, assemble the file and writes the result
* in another specified blkdev. In our emulator layer, we use stdin and stdout
* as those specified blkdevs.
*
* Because the input blkdev needs support for Seek, we buffer it in the emulator
* layer.
*
* Memory layout:
*
* 0x0000 - 0x3fff: ROM code from zasm_glue.asm
* 0x4000 - 0x47ff: RAM for kernel and stack
* 0x4800 - 0x57ff: Userspace code
* 0x5800 - 0xffff: Userspace RAM
*
* I/O Ports:
*
* 0 - stdin / stdout
* 1 - When written to, rewind stdin buffer to the beginning.
*/
// in sync with zasm_glue.asm
#define USER_CODE 0x4800
#define STDIO_PORT 0x00
#define STDIN_SEEK_PORT 0x01
#define FS_DATA_PORT 0x02
#define FS_SEEK_PORT 0x03
#define STDERR_PORT 0x04
// Other consts
#define STDIN_BUFSIZE 0x8000
// When defined, we dump memory instead of dumping expected stdout
//#define MEMDUMP
//#define DEBUG
static Z80Context cpu;
static uint8_t mem[0x10000];
// STDIN buffer, allows us to seek and tell
static uint8_t inpt[STDIN_BUFSIZE];
static int inpt_size;
static int inpt_ptr;
static uint8_t middle_of_seek_tell = 0;
static uint8_t fsdev[0xffff] = {0};
static uint16_t fsdev_size = 0;
static uint16_t fsdev_ptr = 0;
static uint8_t fsdev_middle_of_seek_tell = 0;
static uint8_t io_read(int unused, uint16_t addr)
{
addr &= 0xff;
if (addr == STDIO_PORT) {
if (inpt_ptr < inpt_size) {
return inpt[inpt_ptr++];
} else {
return 0;
}
} else if (addr == STDIN_SEEK_PORT) {
if (middle_of_seek_tell) {
middle_of_seek_tell = 0;
return inpt_ptr & 0xff;
} else {
#ifdef DEBUG
fprintf(stderr, "tell %d\n", inpt_ptr);
#endif
middle_of_seek_tell = 1;
return inpt_ptr >> 8;
}
} else if (addr == FS_DATA_PORT) {
if (fsdev_ptr < fsdev_size) {
return fsdev[fsdev_ptr++];
} else {
return 0;
}
} else if (addr == FS_SEEK_PORT) {
if (fsdev_middle_of_seek_tell) {
fsdev_middle_of_seek_tell = 0;
return fsdev_ptr & 0xff;
} else {
#ifdef DEBUG
fprintf(stderr, "FS tell %d\n", fsdev_ptr);
#endif
fsdev_middle_of_seek_tell = 1;
return fsdev_ptr >> 8;
}
} else {
fprintf(stderr, "Out of bounds I/O read: %d\n", addr);
return 0;
}
}
static void io_write(int unused, uint16_t addr, uint8_t val)
{
addr &= 0xff;
if (addr == STDIO_PORT) {
// When mem-dumping, we don't output regular stuff.
#ifndef MEMDUMP
putchar(val);
#endif
} else if (addr == STDIN_SEEK_PORT) {
if (middle_of_seek_tell) {
inpt_ptr |= val;
middle_of_seek_tell = 0;
#ifdef DEBUG
fprintf(stderr, "seek %d\n", inpt_ptr);
#endif
} else {
inpt_ptr = (val << 8) & 0xff00;
middle_of_seek_tell = 1;
}
} else if (addr == FS_DATA_PORT) {
if (fsdev_ptr < fsdev_size) {
fsdev[fsdev_ptr++] = val;
}
} else if (addr == FS_SEEK_PORT) {
if (fsdev_middle_of_seek_tell) {
fsdev_ptr |= val;
fsdev_middle_of_seek_tell = 0;
#ifdef DEBUG
fprintf(stderr, "FS seek %d\n", fsdev_ptr);
#endif
} else {
fsdev_ptr = (val << 8) & 0xff00;
fsdev_middle_of_seek_tell = 1;
}
} else if (addr == STDERR_PORT) {
fputc(val, stderr);
} else {
fprintf(stderr, "Out of bounds I/O write: %d / %d\n", addr, val);
}
}
static uint8_t mem_read(int unused, uint16_t addr)
{
return mem[addr];
}
static void mem_write(int unused, uint16_t addr, uint8_t val)
{
mem[addr] = val;
}
int main()
{
// initialize memory
for (int i=0; i<sizeof(KERNEL); i++) {
mem[i] = KERNEL[i];
}
for (int i=0; i<sizeof(USERSPACE); i++) {
mem[i+USER_CODE] = USERSPACE[i];
}
for (int i=0; i<sizeof(FSDEV); i++) {
fsdev[i] = FSDEV[i];
}
fsdev_size = sizeof(FSDEV);
// read stdin in buffer
inpt_size = 0;
inpt_ptr = 0;
int c = getchar();
while (c != EOF) {
inpt[inpt_ptr] = c & 0xff;
inpt_ptr++;
if (inpt_ptr == STDIN_BUFSIZE) {
break;
}
c = getchar();
}
inpt_size = inpt_ptr;
inpt_ptr = 0;
Z80RESET(&cpu);
cpu.ioRead = io_read;
cpu.ioWrite = io_write;
cpu.memRead = mem_read;
cpu.memWrite = mem_write;
while (!cpu.halted) {
Z80Execute(&cpu);
}
#ifdef MEMDUMP
for (int i=0; i<0x10000; i++) {
putchar(mem[i]);
}
#endif
fflush(stdout);
int res = cpu.R1.br.A;
if (res != 0) {
fprintf(stderr, "Error %d\n", res);
}
return res;
}