内嵌汇编的错误 -凯发app

realview mdk3.05以上 代码如下： int func (int val) { __asm { mov r7,0xffff0000 mov r0,r0,lsl #16 add r0,r0,r1 } return val; } 错误提示： warning: #1267-d: implicit physical register r7 should be defined as a variable warning: #1267-d: implicit physical register r0 should be defined as a variable error: #549: variable "r0" is used before its value is set warning: #1267-d: implicit physical register r1 should be defined as a variable error: #549: variable "r1" is used before its value is set warning: #177-d: variable "val2" was declared but never referenced

      问题解决：由于嵌套过程中会出现寄存器冲突
      正确例程：
      int func (int val)  {
      int val2;
      __asm
          {
            mov val2,0xffff0000
            mov val,val,lsl #16
          }
          return val val2;
         }