Question

我正在开发虚拟机，并且我的推送指令有问题。它推送显式值而不是引用寄存器中的值，例如：

    0x0064 //this line puts hexadecimal for 100 into register 0
    0x4000 //this is the line i question this will literally put
           //0 into the stack as an explicit value. i want it to
           //put what is in register 0(line 1) into the stack

我在下面列出了我的VM的c源代码：

#include <stdio.h>
#include <stdlib.h>

#define NUM_REGS 16
unsigned short regs[ NUM_REGS ];

unsigned program[] = { 0x10C8, 0x1164, 0x2201, 0x4200, 0x0000 }; 

unsigned stack[10];
int i = 0;

/* program counter */
int pc = 0;

/* fetch the next word from the program */
int fetch()
{
  return program[ pc++ ];
}

/* instruction fields */
int instrNum = 0;
int reg1     = 0;
int reg2     = 0;
int reg3     = 0;
int imm      = 0;

/* decode a word */
void decode( int instr )
{
  instrNum = (instr & 0xF000) >> 12;
  reg1     = (instr & 0xF00) >> 8;
  reg2     = (instr & 0xF0 ) >>  4;
  reg3     = (instr & 0xF  );
  imm      = (instr & 0xFF  );
}

/* the VM runs until this flag becomes 0 */
int running = 1;

/* push element onto stack */
void push( reg )
{
  int a;

  for(a = 10; a <= 10; i--){
    stack[a] = stack[a++];
  }
  stack[0] = reg;

}

/* evaluate the last decoded instruction */
void eval()
{
  switch( instrNum )
  {
    case 0:
      /* halt */
      printf( "halt\n" );
      running = 0;
      break;
    case 1:
      /* loadi */
      printf( "loadi r%d #%d\n", reg1, imm );
      regs[ reg1 ] = imm;
      break;
    case 2:
      /* add */
      printf( "add r%d r%d r%d\n", reg1, reg2, reg3 );
      regs[ reg1 ] = regs[ reg2 ] + regs[ reg3 ];
      break;
    case 3:
      /* sub */
      printf("sub r%d r%d r%d\n", reg1, reg2, reg3);
      regs[reg1] = regs[reg2] - regs[reg3];
      break;
    case 4:
      /* push */
      printf("push r%d\n", reg1);
      push(reg1);
      showStack();
      break;
  }
}

/* display all registers as 4-digit hexadecimal words */
void showRegs()
{
  int i;
  printf( "regs = " );
  for( i=0; i<NUM_REGS; i++ )
    printf( "%04X ", regs[ i ] );
  printf( "\n" );
}

/* show the stack as 4-digit hexadecimal words */
void showStack()
{
  printf("stack = ");
  for(i=0; i<10; i++)
    printf("%04X ", stack[i]);
  printf("\n");
}

  void run()
{
  while( running )
  {
    showRegs();
    int instr = fetch();
    decode( instr );
    eval();
  }
  showRegs();
  showStack();
}

int main( int argc, const char * argv[] )
{
  run();
  return 0;
}

我很肯定其他一切都很实用并且效果很好所以如果你能帮我解决我的虚拟堆栈问题请给我建议

Answer 1

对不起，我只需要添加： stack [0] = regs [reg]; 如“Jester”所述

vm的破坏推送指令

1 个答案: