Registers
Registers all begin with a dollar-symbol ($). The floating point registers are named $f0, $f1, ..., $f31. The general-purpose registers have both names and numbers, and are listed below. When programming in MIPS assembly, it is usually best to use the register names.
| Number | Name | Comments |
|---|---|---|
$0 | $zero, $r0 | Always zero |
$1 | $at | Reserved for assembler |
$2, $3 | $v0, $v1 | First and second return values, respectively |
$4, ..., $7 | $a0, ..., $a3 | First four arguments to functions |
$8, ..., $15 | $t0, ..., $t7 | Temporary registers |
$16, ..., $23 | $s0, ..., $s7 | Saved registers |
$24, $25 | $t8, $t9 | More temporary registers |
$26, $27 | $k0, $k1 | Reserved for kernel (operating system) |
$28 | $gp | Global pointer |
$29 | $sp | Stack pointer |
$30 | $fp | Frame pointer |
$31 | $ra | Return address |
In addition to the general purpose registers, the MIPS32 architecture also includes a number of special purpose registers, which are used to control the operation of the processor and to store certain types of data. These include the program counter (PC) and the status register (SR).
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