OpenCores
URL https://opencores.org/ocsvn/openrisc/openrisc/trunk

Subversion Repositories openrisc

[/] [openrisc/] [trunk/] [orpsocv2/] [sw/] [tests/] [or1200/] [sim/] [or1200-linkregtest.S] - Rev 803

Go to most recent revision | Compare with Previous | Blame | View Log

/*

        Tests of link register behavior in delay slot of l.jal instruction
        
        Testing this:
        l.jal _place
        l.sw 4(r1) r9
        What happens...... (r9 is link register)
Result:
        Appears to confirm that the r9 becomes the return value immediately
        ( at the write-back stage of the l.jal instruction)

        Then testing this:
        l.jal _place
        l.or r9, r0, r0
Result: 
        Writing to link register (r9) in delay slot works, so should be
        avoided (it was illegal according to spec, anyway)
        
*/
//////////////////////////////////////////////////////////////////////
////                                                              ////
//// Copyright (C) 2010 Authors and OPENCORES.ORG                 ////
////                                                              ////
//// This source file may be used and distributed without         ////
//// restriction provided that this copyright statement is not    ////
//// removed from the file and that any derivative work contains  ////
//// the original copyright notice and the associated disclaimer. ////
////                                                              ////
//// This source file is free software; you can redistribute it   ////
//// and/or modify it under the terms of the GNU Lesser General   ////
//// Public License as published by the Free Software Foundation; ////
//// either version 2.1 of the License, or (at your option) any   ////
//// later version.                                               ////
////                                                              ////
//// This source is distributed in the hope that it will be       ////
//// useful, but WITHOUT ANY WARRANTY; without even the implied   ////
//// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR      ////
//// PURPOSE.  See the GNU Lesser General Public License for more ////
//// details.                                                     ////
////                                                              ////
//// You should have received a copy of the GNU Lesser General    ////
//// Public License along with this source; if not, download it   ////
//// from http://www.opencores.org/lgpl.shtml                     ////
////                                                              ////
//////////////////////////////////////////////////////////////////////
        
        
#include "spr-defs.h"
#include "board.h"

/* =================================================== [ exceptions ] === */
        .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
        /* Init the stack */
        .global _stack
        l.movhi r1, hi(_stack)
        l.ori   r1, r1, lo(_stack)
        l.addi  r2, r0, -3
        l.and   r1, r1, r2
        /* 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
        .global _testjalfunc
_start:
        l.addi  r1, r1, -4
        l.movhi r9, hi(0x01234567)
        l.ori   r9, r9, lo(0x01234567)
        l.or    r3, r1, r1 /* copy stack pointer to r3 so we can report it */
        l.nop   0x2
        l.jal   _testjalfunc
        l.sw    0(r1), r9
        l.nop
        l.nop
        l.movhi r3, hi(0x8000000d)
        l.ori   r3, r3, lo(0x8000000d)
        /* Setup some code at address 0x0 */
        l.movhi r4, hi(0x15000000) /* standard l.nop */
        l.ori   r5, r4, 0x2 /* l.nop that will report value in r3 */
        l.sw    0x0(r0), r5 /* Write "l.nop 0x2" to 0x0 */
        l.movhi r6, hi(0xa8600000) /*Assemble register with l.ori r3,r0,0 */
        l.sw    0x4(r0), r6 /* Write "l.ori r3,r0,0" to 0x4*/
        l.ori   r5, r4, 0x1 /* l.nop that will exit simulation */
        l.sw    0x8(r0), r5 /* Write l.nop 0x1 to 0x8 */
        l.sw    0xc(r0), r0 /* Write "l.j 0" to address 0xc */
        l.sw    0x10(r0), r4 /* Write l.nop to 0xc */
        l.nop
        /* Try writing to r9 during delay slot... */
        l.jal   _testjalfunc
        l.or    r9, r0, r0 /* Clear r9 - cause jump to 0 on return */
        l.nop   1


_testjalfunc:
        l.nop
        l.nop
        l.nop
        l.nop
        l.nop
        l.jr    r9
        l.nop

Go to most recent revision | Compare with Previous | Blame | View Log

powered by: WebSVN 2.1.0

© copyright 1999-2024 OpenCores.org, equivalent to Oliscience, all rights reserved. OpenCores®, registered trademark.