asm疑问

[qq_18310569]

// Reset handler stores the address of op code start. The address is offset by 1 because
// it is meant to be used with the BX instruction. BX instruction requires bit[0] of the
// register providing address to branch to be set to 1 for correct execution.
register uint32_t opcode_reset = *((uint32_t *)OPCODE_RESET_ADDRESS);
asm("BX %[reg]" : : [reg] "r" (opcode_reset));
while(1); //end bootloader
return 0;



请问这一句：asm("BX %[reg]" : : [reg] "r" (opcode_reset)); 是什么意思？

[C++实习生]

这不是汇编语法吧。

[日立奔腾浪潮微软松下联想]

就是把存储opcode_reset的那个寄存器替换BX %[reg]中的reg，比如分配的是r0，那么生成的指令就是bx %r0 (gas默认的at&t语法)。