mips - a first example

In the following sample, it shows how to send the input (val) and the output (ret) to assembly block.

/* foo returns (val | 3)
 */
int foo(int val)
{
    int ret;
    __asm__(
    ".set push\n"              // save assembler option
    ".set noreorder\n"         // suppress reordering
    "ori  $2, %1, %2\n"
    "sw $2, %0\n"              // save $2 to ret
    ".set pop\n"               // pop assembler option
    : "=m" (ret)               // ret: memory
    : "r" (val), "n" (3)       // val: read-only register, n: number
    );
    return ret;
}

The real code by dump is:

08804554 :
 8804554: 27bdffd0  addiu sp,sp,-48
 8804558: afbe0020  sw s8,32(sp)
 880455c: 03a0f021  move s8,sp
 8804560: afc40010  sw a0,16(s8)
 8804564: 8fc20010  lw v0,16(s8)
 8804568: 34420003  ori v0,v0,0x3
 880456c: afc20000  sw v0,0(s8)
 8804570: 8fc20000  lw v0,0(s8)
 8804574: 03c0e821  move sp,s8
 8804578: 8fbe0020  lw s8,32(sp)
 880457c: 27bd0030  addiu sp,sp,48
 8804580: 03e00008  jr ra
 8804584: 00000000  nop