/*
 * Conventional register names.
 * taken from file xc.h of https://github.com/jasonkajita/pic32-part-support/
 */

/* Zero register:  Always returns 0 */
#define zero               $0

/* Assembler temporary register:  Reserved for use by the assembler */
#define at_reg             $1
#define AT_reg             $1

/* Return value registers:  Value returned by subroutine */
#define v0                 $2
#define v1                 $3

/* Argument registers:  First few parameters for a subroutine */
#define a0                 $4
#define a1                 $5
#define a2                 $6
#define a3                 $7

/* Subroutine register temporaries:  Registers that subroutines can use
 * without saving
 */
#define t0                 $8
#define t1                 $9
#define t2                 $10
#define t3                 $11
#define t4                 $12
#define t5                 $13
#define t6                 $14
#define t7                 $15
#define t8                 $24
#define t9                 $25

/* Subroutine register variables:  A subroutine that writes one of these
 * must save the old value and restore it before it exists, so the calling
 * routine sees the values preserved
 */
#define s0                 $16
#define s1                 $17
#define s2                 $18
#define s3                 $19
#define s4                 $20
#define s5                 $21
#define s6                 $22
#define s7                 $23

/* Ninth subroutine register variable:  Can either be used as above or
 * as the frame pointer for functions that require one
 */
#define s8                 $30
#define fp                 $30

/* Interrupt/Trap handler registers:  Reserved for use by interrupt/trap
 * handler.  May change under your feet!
 */
#define k0                 $26
#define k1                 $27

/* Global pointer register:  Gives easy access to (some) `static' or `extern'
 * variables
 */
#define gp                 $28

/* Stack pointer register:  Stack pointer */
#define sp                 $29

/* Return address register:  Contains the return address for the subroutine */
#define ra                 $31