Register Number | Alternative Name | Description |
---|---|---|
0 | $zero | Always the value 0. |
1 | $at | assembler temporary, reserved by the assembler. |
2 | $v0 | (values) from expression evaluation and function results. |
3 | $v1 | |
4 | $a0 | $a0 - $a3 (arguments) First four parameters for subroutine. Not preserved across procedure calls |
5 | $a1 | |
6 | $a2 | |
7 | $a3 | |
8 | $t0 | $t0 - $t7 (temporaries) Caller saved if needed. Subroutines can use w/out saving. Not preserved across procedure calls. |
9 | $t1 | |
10 | $t2 | |
11 | $t3 | |
12 | $t4 | |
13 | $t5 | |
14 | $t6 | |
15 | $t7 | |
16 | $s0 | $s0 - $s7 (saved values) - Callee saved. A subroutine using one of these must save original and restore it before exiting. Preserved across procedure calls. |
17 | $s1 | |
18 | $s2 | |
19 | $s3 | |
20 | $s4 | |
21 | $s5 | |
22 | $s6 | |
23 | $s7 | |
24 | $t8 | $t8 - $t9 (temporaries) Similar to $t0 - $t7 above. |
25 | $t9 | |
26 | $k0 | $k0 - $k1 reserved for use by the interrupt/trap handler. |
27 | $k1 | |
28 | $gp | global pointer. Points to middle of 64K block of memory in the static data segment. |
29 | $sp | stack pointer. Points to the top of the stack. |
30 | $fp or $s8 | saved value or frame pointer. Preserved across procedure calls. |
31 | $ra | return address |