Subversion Repositories mips32r1

###############################################################################
# TITLE: Exception Vectors
# AUTHOR: Grant Ayers (ayers@cs.utah.edu)
# DATE: 23 May 2012
# FILENAME: exceptions.asm
# PROJECT: University of Utah XUM Single Core
# DESCRIPTION:
#   Provides the exception vectors which jump to
#   exception-handling routines.
#
###############################################################################

        .text
        .balign 4
        .set    noreorder
        .set    noat

exc_save:
        # Save all registers except k0 k1 sp ra
        addiu   $sp, $sp, -112
        sw      $1,    0($sp)
        sw      $2,    4($sp)
        sw      $3,    8($sp)
        sw      $4,   12($sp)
        sw      $5,   16($sp)
        sw      $6,   20($sp)
        sw      $7,   24($sp)
        sw      $8,   28($sp)
        sw      $9,   32($sp)
        sw      $10,  36($sp)
        sw      $11,  40($sp)
        sw      $12,  44($sp)
        sw      $13,  48($sp)
        sw      $14,  52($sp)
        sw      $15,  56($sp)
        sw      $16,  60($sp)
        sw      $17,  64($sp)
        sw      $18,  68($sp)
        sw      $19,  72($sp)
        sw      $20,  76($sp)
        sw      $21,  80($sp)
        sw      $22,  84($sp)
        sw      $23,  88($sp)
        sw      $24,  92($sp)
        sw      $25,  96($sp)
        sw      $28, 100($sp)
        jr      $ra
        sw      $30, 104($sp)

exc_restore:
        # Restore all registers except k0 k1 sp ra
        lw      $1,    0($sp)
        lw      $2,    4($sp)
        lw      $3,    8($sp)
        lw      $4,   12($sp)
        lw      $5,   16($sp)
        lw      $6,   20($sp)
        lw      $7,   24($sp)
        lw      $8,   28($sp)
        lw      $9,   32($sp)
        lw      $10,  36($sp)
        lw      $11,  40($sp)
        lw      $12,  44($sp)
        lw      $13,  48($sp)
        lw      $14,  52($sp)
        lw      $15,  56($sp)
        lw      $16,  60($sp)
        lw      $17,  64($sp)
        lw      $18,  68($sp)
        lw      $19,  72($sp)
        lw      $20,  76($sp)
        lw      $21,  80($sp)
        lw      $22,  84($sp)
        lw      $23,  88($sp)
        lw      $24,  92($sp)
        lw      $25,  96($sp)
        lw      $28, 100($sp)
        lw      $30, 104($sp)
        jr      $ra
        addiu   $sp, $sp, 112


        .global mips32_general_exception
        .ent    mips32_general_exception
mips32_general_exception:
        or      $26, $0, $ra
        jal     exc_save
        nop
        mfc0    $27, $13, 0             # Read Cause which has ExcCode bits
        srl     $27, $27, 2             # Extract exception code to $k1
        andi    $27, $27, 0x001f

        la      $ra, $end_exception     # Jump to the appropriate handler
        addiu   $t0, $0, 4
        addiu   $t1, $0, 5
        addiu   $t2, $0, 8
        addiu   $t3, $0, 9
        beq     $t0, $27, mips32_handler_AdEL
        addiu   $t0, $0, 10
        beq     $t1, $27, mips32_handler_AdES
        addiu   $t1, $0, 11
        beq     $t2, $27, mips32_handler_Sys
        addiu   $t2, $0, 12
        beq     $t3, $27, mips32_handler_Bp
        addiu   $t3, $0, 13
        beq     $t0, $27, mips32_handler_RI
        nop
        beq     $t1, $27, mips32_handler_CpU
        nop
        beq     $t2, $27, mips32_handler_Ov
        nop
        beq     $t3, $27, mips32_handler_Tr
        nop

$end_exception:
        jal     exc_restore
        xor     $27, $0, $0
        or      $ra, $0, $26
        xor     $26, $0, $0
        eret
        .end    mips32_general_exception



### "Special" Interrupt Vector: Cause_IV must be set.
        
        .ent    mips32_interrupt_exception
        .global mips32_interrupt_exception
mips32_interrupt_exception:
        mfc0    $26, $12, 0             # Status register for IM bits
        mfc0    $27, $13, 0             # Cause register for IP bits
        and     $26, $26, $27           # Extract pending, unmasked interrupts
        srl     $26, $26, 8
        andi    $26, $26, 0x00ff

        addu    $27, $0, $ra
        jal     exc_save        
        clz     $26, $26
        la      $ra, $end_interrupt     # All C functions will return here
        addiu   $t0, $0, 24
        addiu   $t1, $0, 25
        addiu   $t2, $0, 26
        beq     $26, $t0, mips32_handler_HwInt5
        addiu   $t0, $0, 27
        beq     $26, $t1, mips32_handler_HwInt4
        addiu   $t1, $0, 28
        beq     $26, $t2, mips32_handler_HwInt3
        addiu   $t2, $0, 29
        beq     $26, $t0, mips32_handler_HwInt2
        addiu   $t0, $0, 30
        beq     $26, $t1, mips32_handler_HwInt1
        addiu   $t1, $0, 31
        beq     $26, $t2, mips32_handler_HwInt0
        nop
        beq     $26, $t0, mips32_handler_SwInt1
        nop
        beq     $26, $t1, mips32_handler_SwInt0
        nop
        

$end_interrupt:
        jal     exc_restore
        mfc0    $26, $9, 0              # Clear HwInt5 if applicable
        or      $ra, $0, $27
        eret
        .end    mips32_interrupt_exception