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/*
        Simple test to exercise cache writeback

        Fills all of cache, then reads data back.

        Julius Baxter, ORSoC AB, <julius.baxter@orsoc.se>
        
*/
#include "spr-defs.h"

#define NUM_LINES 4
#define BYTES_PER_LINE 32
#define WORDS_PER_LINE 8
        
        .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 line 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

        /* r8 used as counter for words on line - do 128/4 = 32 writes */
        l.movhi r8,0
        
wr_words_loop:
        /* r9 is data - top 16-bits is line number, bottom 16 is word */
        l.slli  r9,r2,16
        l.or    r9,r9,r8

        /* report value we're writing */
        l.ori   r3,r9,0
        l.nop   0x2

        /* report address where writing */
        l.ori   r3,r6,0
        l.nop   0x2
        
        /* do memory access */
        l.sw    0(r6),r9        /* Write counter to this address */

        l.addi  r6,r6,4         /* Increment memory pointer */

        l.sfnei r8,WORDS_PER_LINE-1     /* Finished filling this line? */
        l.bf    wr_words_loop
        l.addi  r8,r8,1         /* Increment word counter */

        /* end of word write loop */
        
        l.sfeqi r2,NUM_LINES-1          /* Done all lines? */
        l.bnf   wr_loop
        l.addi  r2,r2,1         /* increment line counter */

        /* end of line write loop */
        
        /* reset line 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

        /* r8 used as counter for words on line - do 128/4 = 32 reads */
        l.movhi r8,0
        
rd_words_loop:
        /* r9 is data - top 16-bits is line number, bottom 16 is word */
        l.slli  r9,r2,16
        l.or    r9,r9,r8

        /* report address where reading */
        l.ori   r3,r6,0
        l.nop   0x2
        
        /* do memory access */
        l.lwz   r10, 0(r6)      /* Read data */

        /* report what we *should* read */
        l.ori   r3,r9,0
        l.nop   0x2
        
        /* report what we read */
        l.ori   r3,r10,0
        l.nop   0x2

        l.sfne  r9,r10          /* Does data equal what it should? */
        l.bf    fail
        
        l.addi  r6,r6,4         /* Increment memory pointer */

        l.sfnei r8,WORDS_PER_LINE-1     /* Finished reading this line? */
        l.bf    rd_words_loop
        l.addi  r8,r8,1         /* Increment word counter */

        /* end of word read loop */     

        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