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https://github.com/hsoft/collapseos.git
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196 lines
4.2 KiB
C
196 lines
4.2 KiB
C
/* Common code between forth and stage binaries.
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They all run on the same kind of virtual machine: A z80 CPU, 64K of RAM/ROM.
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*/
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#include <string.h>
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#include "emul.h"
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// Port for block reads. Each read or write has to be done in 5 IO writes:
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// 1 - r/w. 1 for read, 2 for write.
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// 2 - blkid MSB
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// 3 - blkid LSB
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// 4 - dest addr MSB
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// 5 - dest addr LSB
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#define BLK_PORT 0x03
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#ifndef BLKFS_PATH
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#error BLKFS_PATH needed
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#endif
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#ifndef FBIN_PATH
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#error FBIN_PATH needed
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#endif
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static Machine m;
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static ushort traceval = 0;
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static uint64_t blkop = 0; // 5 bytes
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static FILE *blkfp;
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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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IORD fn = m.iord[addr];
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if (fn != NULL) {
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return fn();
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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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IOWR fn = m.iowr[addr];
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if (fn != NULL) {
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fn(val);
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} else {
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fprintf(stderr, "Out of bounds I/O write: %d / %d (0x%x)\n", addr, val, val);
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}
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}
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static void iowr_blk(uint8_t val)
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{
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blkop <<= 8;
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blkop |= val;
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uint8_t rw = blkop >> 32;
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if (rw) {
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uint16_t blkid = (blkop >> 16);
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uint16_t dest = blkop & 0xffff;
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blkop = 0;
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fseek(blkfp, blkid*1024, SEEK_SET);
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if (rw==2) { // write
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fwrite(&m.mem[dest], 1024, 1, blkfp);
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} else { // read
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fread(&m.mem[dest], 1024, 1, blkfp);
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}
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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 m.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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if (addr < m.ramstart) {
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fprintf(stderr, "Writing to ROM (%d)!\n", addr);
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emul_memdump();
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fprintf(stderr, "Press any key to continue...\n");
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while (getchar() > 0x100);
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}
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m.mem[addr] = val;
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}
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Machine* emul_init()
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{
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fprintf(stderr, "Using blkfs %s\n", BLKFS_PATH);
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blkfp = fopen(BLKFS_PATH, "r+");
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if (!blkfp) {
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fprintf(stderr, "Can't open\n");
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return NULL;
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}
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fseek(blkfp, 0, SEEK_END);
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if (ftell(blkfp) < 100 * 1024) {
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fclose(blkfp);
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fprintf(stderr, "emul/blkfs too small, something's wrong, aborting.\n");
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return NULL;
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}
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fseek(blkfp, 0, SEEK_SET);
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// initialize memory
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memset(m.mem, 0, 0x10000);
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FILE *bfp = fopen(FBIN_PATH, "r");
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if (!bfp) {
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fprintf(stderr, "Can't open forth.bin\n");
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return NULL;
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}
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int i = 0;
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int c = getc(bfp);
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while (c != EOF) {
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m.mem[i++] = c;
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c = getc(bfp);
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}
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fclose(bfp);
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m.ramstart = 0;
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m.minsp = 0xffff;
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m.maxix = 0;
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for (int i=0; i<0x100; i++) {
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m.iord[i] = NULL;
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m.iowr[i] = NULL;
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}
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Z80RESET(&m.cpu);
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m.cpu.memRead = mem_read;
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m.cpu.memWrite = mem_write;
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m.cpu.ioRead = io_read;
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m.cpu.ioWrite = io_write;
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m.iowr[BLK_PORT] = iowr_blk;
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return &m;
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}
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void emul_deinit()
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{
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fclose(blkfp);
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}
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bool emul_step()
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{
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if (!m.cpu.halted) {
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Z80Execute(&m.cpu);
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ushort newsp = m.cpu.R1.wr.SP;
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if (newsp != 0 && newsp < m.minsp) {
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m.minsp = newsp;
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}
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if (m.cpu.R1.wr.IX > m.maxix) {
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m.maxix = m.cpu.R1.wr.IX;
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}
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return true;
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} else {
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return false;
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}
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}
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bool emul_steps(unsigned int steps)
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{
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while (steps) {
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if (!emul_step()) {
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return false;
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}
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steps--;
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}
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return true;
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}
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void emul_loop()
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{
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while (emul_step());
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}
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void emul_trace(ushort addr)
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{
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ushort newval = m.mem[addr+1] << 8 | m.mem[addr];
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if (newval != traceval) {
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traceval = newval;
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fprintf(stderr, "trace: %04x PC: %04x\n", traceval, m.cpu.PC);
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}
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}
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void emul_memdump()
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{
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fprintf(stderr, "Dumping memory to memdump. PC %04x\n", m.cpu.PC);
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FILE *fp = fopen("memdump", "w");
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fwrite(m.mem, 0x10000, 1, fp);
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fclose(fp);
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}
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void emul_debugstr(char *s)
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{
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sprintf(s, "SP %04x (%04x) IX %04x (%04x)",
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m.cpu.R1.wr.SP, m.minsp, m.cpu.R1.wr.IX, m.maxix);
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}
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void emul_printdebug()
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{
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fprintf(stderr, "Min SP: %04x\n", m.minsp);
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fprintf(stderr, "Max IX: %04x\n", m.maxix);
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}
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