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collapseos/tools/emul/emul.c
Virgil Dupras 66dacd1816 tools/emul: add "Min SP" debug value
This gives the maximum size of the stack at any given moment during the
execution of the program. It's useful to figure out if the stack gets
dangerously close to the heap.
2019-12-02 17:44:54 -05:00

88 lines
1.6 KiB
C

/* Common code between shell, zasm and runbin.
They all run on the same kind of virtual machine: A z80 CPU, 64K of RAM/ROM.
*/
#include <string.h>
#include "emul.h"
static Machine m;
static uint8_t io_read(int unused, uint16_t addr)
{
addr &= 0xff;
IORD fn = m.iord[addr];
if (fn != NULL) {
return fn();
} 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;
IOWR fn = m.iowr[addr];
if (fn != NULL) {
fn(val);
} else {
fprintf(stderr, "Out of bounds I/O write: %d / %d (0x%x)\n", addr, val, val);
}
}
static uint8_t mem_read(int unused, uint16_t addr)
{
return m.mem[addr];
}
static void mem_write(int unused, uint16_t addr, uint8_t val)
{
if (addr < m.ramstart) {
fprintf(stderr, "Writing to ROM (%d)!\n", addr);
}
m.mem[addr] = val;
}
Machine* emul_init()
{
memset(m.mem, 0, 0x10000);
m.ramstart = 0;
m.minsp = 0xffff;
for (int i=0; i<0x100; i++) {
m.iord[i] = NULL;
m.iowr[i] = NULL;
}
Z80RESET(&m.cpu);
m.cpu.memRead = mem_read;
m.cpu.memWrite = mem_write;
m.cpu.ioRead = io_read;
m.cpu.ioWrite = io_write;
return &m;
}
bool emul_step()
{
if (!m.cpu.halted) {
Z80Execute(&m.cpu);
ushort newsp = m.cpu.R1.wr.SP;
if (newsp != 0 && newsp < m.minsp) {
m.minsp = newsp;
}
return true;
} else {
return false;
}
}
void emul_loop()
{
while (emul_step());
}
void emul_printdebug()
{
fprintf(stderr, "Min SP: %04x\n", m.minsp);
}