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