TinyVM: A lightweight, fast virtual machine in < 500 lines of ANSI C

eookoo

昨天在 Hacker News 看到這個 post, 覺得對學 C 的會很有幫助. Tiny Virtual Machine 的代碼少於 500 行, 看起來不累又容易理解.

可以去 Github 下載: https://github.com/GenTiradentes/tinyvm

也可以直接下載附件
TinyVM.zip (12.35 KB, 下载次数: 81)

2011-07-04 00:00 上传

点击文件名下载附件

peidright

it is really good.

greensnow

http://www.reddit.com/r/tinycode/

koolcoy

不解释{:3_191:}

1. 
   
2. void run_vm(virtual_machine* vm)
   
3. {
   
4. int instr_idx = vm->pProgram->start;
   
5. 
   
6. for(;vm->pProgram->instr[instr_idx] != END; ++instr_idx)
   
7. {
   
8. int *arg0 = vm->pProgram->args[instr_idx][0], *arg1 = vm->pProgram->args[instr_idx][1];
   
9. 
   
10. switch(vm->pProgram->instr[instr_idx])
    
11. {
    
12. case MOV: *arg0 = *arg1; break;
    
13. case PUSH: stack_push(vm->pStack, arg0); break;
    
14. case POP: stack_pop(vm->pStack, arg0); break;
    
15. case INC: ++(*arg0); break;
    
16. case DEC: --(*arg0); break;
    
17. case ADD: *arg0 += *arg1; break;
    
18. case SUB: *arg0 -= *arg1; break;
    
19. case MUL: *arg0 *= *arg1; break;
    
20. case DIV: *arg0 /= *arg1; break;
    
21. case MOD: vm->pMemory->remainder = *arg0 % *arg1; break;
    
22. case REM: *arg0 = vm->pMemory->remainder; break;
    
23. case NOT: *arg0 = ~(*arg0); break;
    
24. case XOR: *arg0 ^= *arg1; break;
    
25. case OR: *arg0 |= *arg1; break;
    
26. case AND: *arg0 &= *arg1; break;
    
27. case SHL: *arg0 <<= *arg1; break;
    
28. case SHR: *arg0 >>= *arg1; break;
    
29. case CMP: vm->pMemory->FLAGS = ((*arg0 == *arg1) | (*arg0 > *arg1) << 1); break;
    
30. case JMP: instr_idx = *arg0 - 1; break;
    
31. case JE: if(vm->pMemory->FLAGS & 0x1) instr_idx = *arg0 - 1; break;
    
32. case JNE: if(!(vm->pMemory->FLAGS & 0x1)) instr_idx = *arg0 - 1; break;
    
33. case JG: if(vm->pMemory->FLAGS & 0x2) instr_idx = *arg0 - 1; break;
    
34. case JGE: if(vm->pMemory->FLAGS & 0x3) instr_idx = *arg0 - 1; break;
    
35. case JL: if(!(vm->pMemory->FLAGS & 0x3)) instr_idx = *arg0 - 1; break;
    
36. case JLE: if(!(vm->pMemory->FLAGS & 0x2)) instr_idx = *arg0 - 1; break;
    
37. };
    
38. }
    
39. }
    

复制代码

liexusong

还好，不过不够深入

peidright

回复 3# greensnow

good ! good!