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/*
        Simple test to exercise cache writeback

        Hardcoded for cache with 4 lines of 32 bytes.
        
        Julius Baxter, ORSoC AB, <julius.baxter@orsoc.se>
        
*/
#include "spr-defs.h"

#define NUM_LINES 4
#define BYTES_PER_LINE 32
        
        .section .vectors, "ax"

/* ---[ 0x100: RESET exception ]----------------------------------------- */
        .org 0x100      
        l.movhi r0, 0
        /* Clear status register */
        l.ori r1, r0, SPR_SR_SM
        l.mtspr r0, r1, SPR_SR
        /* Clear timer  */
        l.mtspr r0, r0, SPR_TTMR

        /* Jump to program initialisation code */
        .global _start
        l.movhi r4, hi(_start)
        l.ori r4, r4, lo(_start)
        l.jr    r4
        l.nop


/* =================================================== [ text ] === */
        .section .text

/* =================================================== [ start ] === */ 

        .global _start

_start: 
        l.movhi r1,hi(_stack)
        l.ori   r1,r1,lo(_stack)
        l.addi  r2, r0, -3
        l.and   r1, r1, r2

        l.movhi r2,0    /*r2 is counter */

        /* Write data into addresses that should step through the
        lines of the cache */

        l.addi  r5,r0,-(BYTES_PER_LINE-1)
        l.and   r4,r1,r5        /* r4 has base address of place to access */
        l.addi  r4,r4,BYTES_PER_LINE    /* Go to safe address, past top of stack */

        /* report this address */
        l.ori   r3,r4,0
        l.nop   0x2

wr_loop:
        l.muli  r5,r2,BYTES_PER_LINE    /* offset from base address */
        l.add   r6,r5,r4        /* Address to write to (line offset + base) */

        /* report this address */
        l.ori   r3,r6,0
        l.nop   0x2

        /* report counter */
        l.ori   r3,r2,0
        l.nop   0x2

        /* do memory access */
        l.sw    0(r6),r2        /* Write counter to this address */

        l.sfeqi r2,(NUM_LINES-1)        /* Done all lines? */
        l.bnf   wr_loop
        l.addi  r2,r2,1         /* increment line counter */

        /* end of write loop */
        
        /* reset counter */
        l.movhi r2,0
        
rd_loop:
        l.muli  r5,r2,BYTES_PER_LINE    /* offset from base address */
        l.add   r6,r5,r4        /* Address to write to (line offset + base) */

        /* report this address */
        l.ori   r3,r6,0
        l.nop   0x2

        /* report counter */
        l.ori   r3,r2,0
        l.nop   0x2

        /* do memory access */
        l.lwz   r7,0(r6)        /* load value */

        /* should equal r2 */
        l.sfne  r2,r7
        l.bf    fail
        l.nop   

        l.sfeqi r2,(NUM_LINES-1)        /* Done all lines? */
        l.bnf   rd_loop
        l.addi  r2,r2,1         /* increment line counter */

        /* end of read loop */
pass:
        l.movhi r3,0x8000
        l.ori   r3,r3,0x000d
        l.nop   0x2
        l.movhi r3,0
        l.nop   0x1

fail:
        l.movhi r3,0xbaaa
        l.ori   r3,r3,0xaaad
        l.nop   0x1