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ack/plat/linux68k/emu/sim.c

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C
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#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <stdint.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <errno.h>
#include "sim.h"
#include "m68k.h"
void disassemble_program();
#define ADDRESS_MASK 0xffffffff
#define RAM_BASE 0x08000000
#define RAM_TOP 0x08100000
#define BRK_TOP (RAM_TOP - 0x1000)
#define INIT_SP RAM_TOP
#define INIT_PC 0x08000054
/* Read/write macros */
#define READ_BYTE(BASE, ADDR) (BASE)[ADDR]
#define READ_WORD(BASE, ADDR) (((BASE)[ADDR]<<8) | \
(BASE)[(ADDR)+1])
#define READ_LONG(BASE, ADDR) (((BASE)[ADDR]<<24) | \
((BASE)[(ADDR)+1]<<16) | \
((BASE)[(ADDR)+2]<<8) | \
(BASE)[(ADDR)+3])
#define WRITE_BYTE(BASE, ADDR, VAL) (BASE)[ADDR] = (VAL)&0xff
#define WRITE_WORD(BASE, ADDR, VAL) (BASE)[ADDR] = ((VAL)>>8) & 0xff; \
(BASE)[(ADDR)+1] = (VAL)&0xff
#define WRITE_LONG(BASE, ADDR, VAL) (BASE)[ADDR] = ((VAL)>>24) & 0xff; \
(BASE)[(ADDR)+1] = ((VAL)>>16)&0xff; \
(BASE)[(ADDR)+2] = ((VAL)>>8)&0xff; \
(BASE)[(ADDR)+3] = (VAL)&0xff
static void exit_error(char* fmt, ...);
static void emulated_syscall(void);
uint32_t cpu_read_byte(uint32_t address);
uint32_t cpu_read_word(uint32_t address);
uint32_t cpu_read_long(uint32_t address);
void cpu_write_byte(uint32_t address, uint32_t value);
void cpu_write_word(uint32_t address, uint32_t value);
void cpu_write_long(uint32_t address, uint32_t value);
unsigned char g_ram[RAM_TOP - RAM_BASE];
uint32_t brkbase = RAM_BASE;
uint32_t brkpos = RAM_BASE;
uint32_t entrypoint = RAM_BASE;
/* Exit with an error message. Use printf syntax. */
void exit_error(char* fmt, ...)
{
static int guard_val = 0;
char buff[100];
uint32_t pc;
va_list args;
if(guard_val)
return;
else
guard_val = 1;
va_start(args, fmt);
vfprintf(stderr, fmt, args);
va_end(args);
fprintf(stderr, "\n");
pc = m68k_get_reg(NULL, M68K_REG_PPC);
m68k_disassemble(buff, pc, M68K_CPU_TYPE_68020);
fprintf(stderr, "At %04x: %s\n", pc, buff);
exit(EXIT_FAILURE);
}
static inline uint32_t transform_address(uint32_t address)
{
uint32_t i = (address & ADDRESS_MASK) - RAM_BASE;
if (i >= (uint32_t)(RAM_TOP - RAM_BASE))
exit_error("Attempted to read from RAM address %08x", address);
return i;
}
uint32_t cpu_read_long(uint32_t address)
{
switch (address)
{
case 0x00: return INIT_SP;
case 0x04: return entrypoint;
case 0x80: emulated_syscall(); return 0x10000;
case 0x10000: return 0x4e734e73; /* rte; rte */
case 0x10004: return 0;
default:
{
uint32_t value = READ_LONG(g_ram, transform_address(address));
#if 0
printf("read %08x from %08x\n", value, address);
#endif
return value;
}
}
}
uint32_t cpu_read_word(uint32_t address)
{
uint32_t l = cpu_read_long(address & ~3);
l >>= 16 - (address & 2)*8;
return l & 0xffff;
}
uint32_t cpu_read_byte(uint32_t address)
{
uint32_t l = cpu_read_long(address & ~3);
l >>= 24 - (address & 3)*8;
return l & 0xff;
}
uint32_t cpu_read_word_dasm(uint32_t address)
{
return cpu_read_word(address);
}
uint32_t cpu_read_long_dasm(uint32_t address)
{
return cpu_read_long(address);
}
/* Write data to RAM or a device */
void cpu_write_byte(uint32_t address, uint32_t value)
{
WRITE_BYTE(g_ram, transform_address(address), value);
}
void cpu_write_word(uint32_t address, uint32_t value)
{
WRITE_WORD(g_ram, transform_address(address), value);
}
void cpu_write_long(uint32_t address, uint32_t value)
{
WRITE_LONG(g_ram, transform_address(address), value);
}
/* Disassembler */
void make_hex(char* buff, uint32_t pc, uint32_t length)
{
char* ptr = buff;
for(;length>0;length -= 2)
{
sprintf(ptr, "%04x", cpu_read_word_dasm(pc));
pc += 2;
ptr += 4;
if(length > 2)
*ptr++ = ' ';
}
}
void disassemble_program()
{
uint32_t pc;
uint32_t instr_size;
char buff[100];
char buff2[100];
pc = cpu_read_long_dasm(4);
while(pc <= 0x16e)
{
instr_size = m68k_disassemble(buff, pc, M68K_CPU_TYPE_68000);
make_hex(buff2, pc, instr_size);
printf("%03x: %-20s: %s\n", pc, buff2, buff);
pc += instr_size;
}
fflush(stdout);
}
void cpu_instr_callback()
{
uint32_t pc = m68k_get_reg(NULL, M68K_REG_PC);
if (pc == 0xc)
exit_error("address exception");
/* The following code would print out instructions as they are executed */
#if 0
static char buff[100];
static char buff2[100];
static uint32_t instr_size;
instr_size = m68k_disassemble(buff, pc, M68K_CPU_TYPE_68020);
make_hex(buff2, pc, instr_size);
printf("E %03x: %-20s: %s\n", pc, buff2, buff);
printf(" d0: %08x d1: %08x d2: %08x d3: %08x d4: %08x d5: %08x d6: %08x d7: %08x\n",
m68k_get_reg(NULL, M68K_REG_D0),
m68k_get_reg(NULL, M68K_REG_D1),
m68k_get_reg(NULL, M68K_REG_D2),
m68k_get_reg(NULL, M68K_REG_D3),
m68k_get_reg(NULL, M68K_REG_D4),
m68k_get_reg(NULL, M68K_REG_D5),
m68k_get_reg(NULL, M68K_REG_D6),
m68k_get_reg(NULL, M68K_REG_D7));
printf(" a0: %08x a1: %08x a2: %08x a3: %08x a4: %08x a5: %08x a6: %08x a7: %08x\n",
m68k_get_reg(NULL, M68K_REG_A0),
m68k_get_reg(NULL, M68K_REG_A1),
m68k_get_reg(NULL, M68K_REG_A2),
m68k_get_reg(NULL, M68K_REG_A3),
m68k_get_reg(NULL, M68K_REG_A4),
m68k_get_reg(NULL, M68K_REG_A5),
m68k_get_reg(NULL, M68K_REG_A6),
m68k_get_reg(NULL, M68K_REG_A7));
fflush(stdout);
#endif
}
static void emulated_syscall(void)
{
int s = m68k_get_reg(NULL, M68K_REG_D0);
switch (s)
{
case 1: /* exit */
exit(m68k_get_reg(NULL, M68K_REG_D1));
case 4: /* write */
{
uint32_t fd = m68k_get_reg(NULL, M68K_REG_D1);
uint32_t ptr = m68k_get_reg(NULL, M68K_REG_D2);
uint32_t len = m68k_get_reg(NULL, M68K_REG_D3);
m68k_set_reg(M68K_REG_D0, write(fd, g_ram + transform_address(ptr), len));
break;
}
case 45: /* brk */
{
uint32_t newpos = m68k_get_reg(NULL, M68K_REG_D1);
if (newpos == 0)
m68k_set_reg(M68K_REG_D0, brkpos);
else if ((newpos < brkbase) || (newpos >= BRK_TOP))
m68k_set_reg(M68K_REG_D0, -ENOMEM);
else
{
brkpos = newpos;
m68k_set_reg(M68K_REG_D0, 0);
}
break;
}
case 54: /* ioctl */
m68k_set_reg(M68K_REG_D0, 0);
break;
default:
exit_error("unknown system call %d", s);
}
}
static void load_program(FILE* fd)
{
fseek(fd, 0, SEEK_SET);
if (fread(g_ram, 1, 0x34, fd) != 0x34)
exit_error("couldn't read ELF header");
uint32_t phoff = READ_LONG(g_ram, 0x1c);
uint16_t phentsize = READ_WORD(g_ram, 0x2a);
uint16_t phnum = READ_WORD(g_ram, 0x2c);
entrypoint = READ_LONG(g_ram, 0x18);
if ((phentsize != 0x20) || (phnum != 1))
exit_error("unsupported ELF file");
fseek(fd, phoff, SEEK_SET);
if (fread(g_ram, 1, phentsize, fd) != phentsize)
exit_error("couldn't read program header");
uint32_t offset = READ_LONG(g_ram, 0x04);
uint32_t vaddr = READ_LONG(g_ram, 0x08);
uint32_t filesz = READ_LONG(g_ram, 0x10);
uint32_t memsz = READ_LONG(g_ram, 0x14);
brkbase = brkpos = vaddr + memsz;
uint32_t vaddroffset = transform_address(vaddr);
transform_address(vaddr + memsz); /* bounds check */
memset(g_ram+vaddroffset, 0, memsz);
fseek(fd, offset, SEEK_SET);
if (fread(g_ram+vaddroffset, 1, filesz, fd) != filesz)
exit_error("couldn't read program data");
}
/* The main loop */
int main(int argc, char* argv[])
{
FILE* fhandle;
if(argc != 2)
{
printf("Usage: sim <program file>\n");
exit(-1);
}
if((fhandle = fopen(argv[1], "rb")) == NULL)
exit_error("Unable to open %s", argv[1]);
load_program(fhandle);
// disassemble_program();
m68k_set_cpu_type(M68K_CPU_TYPE_68020);
m68k_init();
m68k_pulse_reset();
/* On entry, the Linux stack looks like this.
*
* sp+.. NULL
* sp+8+(4*argc) env (X quads)
* sp+4+(4*argc) NULL
* sp+4 argv (argc quads)
* sp argc
*
* We'll set it up with a bodgy stack frame with argc=0 just to keep the
* startup code happy.
*/
{
uint32_t sp = INIT_SP;
cpu_write_long(sp -= 4, 0);
uint32_t envp = sp;
cpu_write_long(sp -= 4, envp);
cpu_write_long(sp -= 4, 0);
unsigned long argv = sp;
cpu_write_long(sp -= 4, argv);
cpu_write_long(sp -= 4, 0);
m68k_set_reg(M68K_REG_SP, sp);
}
for (;;)
m68k_execute(100000);
return 0;
}
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