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##################################################################
# TITLE: Opcode Tester
# AUTHOR: Steve Rhoads (rhoadss@yahoo.com)
# DATE CREATED: 1/10/02
# FILENAME: opcodes.asm
# PROJECT: MIPS CPU core
# COPYRIGHT: Software placed into the public domain by the author.
#    Software 'as is' without warranty.  Author liable for nothing.
# DESCRIPTION:
#    This assembly file tests all of the opcodes supported by the
#    MIPS-lite core.
#    This test assumes that address 0xffff is the UART write register
#    Successful tests will print out "A" or "AB" or "ABC" or ....
#    Missing letters or letters out of order indicate a failure.
##################################################################
        .text
        .align  2
        .globl  entry
        .ent    entry
entry:
   .set noreorder

   #These four instructions must be the first instructions
   #convert.exe will correctly initialize $gp
   lui   $gp,0
   ori   $gp,$gp,0
   #convert.exe will set $4=.sbss_start $5=.bss_end
   ori   $4,$0,0
   ori   $5,$0,0

   mtc0  $0,$12             #disable interrupts
   ori   $20,$0,0xffff      #serial port write address
   ori   $21,$0,'\n'        #<CR> letter
   ori   $22,$0,'X'         #'X' letter

   ######################################
   #Arithmetic Instructions
   ######################################
   ori   $2,$0,'A'
   sb    $2,0($20)
   ori   $2,$0,'r'
   sb    $2,0($20)
   ori   $2,$0,'i'
   sb    $2,0($20)
   ori   $2,$0,'t'
   sb    $2,0($20)
   ori   $2,$0,'h'
   sb    $2,0($20)
   sb    $21,0($20)

   #a: ADD
   ori   $2,$0,'a'
   sb    $2,0($20)
   ori   $3,$0,5
   ori   $4,$0,60
   add   $2,$3,$4
   sb    $2,0($20)    #A
   sb    $21,0($20)

   #b: ADDI
   ori   $2,$0,'b'
   sb    $2,0($20)
   ori   $4,$0,60
   addi  $2,$4,5
   sb    $2,0($20)    #A
   sb    $21,0($20)

   #c: ADDIU
   ori   $2,$0,'c'
   sb    $2,0($20)
   ori   $4,$0,50
   addiu $5,$4,15
   sb    $5,0($20)    #A
   sb    $21,0($20)

   #d: ADDU
   ori   $2,$0,'d'
   sb    $2,0($20)
   ori   $3,$0,5
   ori   $4,$0,60
   add   $2,$3,$4
   sb    $2,0($20)    #A
   sb    $21,0($20)

   #e: DIV
   ori   $2,$0,'e'
   sb    $2,0($20)
   ori   $2,$0,65*117+41
   ori   $3,$0,117
   div   $2,$3
   nop
   mflo  $4
   sb    $4,0($20)    #A
   mfhi  $4
   addi  $4,$4,66-41
   sb    $4,0($20)    #B
   li    $2,-67*19
   ori   $3,$0,19
   div   $2,$3
   nop
   mflo  $4
   sub   $4,$0,$4
   sb    $4,0($20)    #C
   ori   $2,$0,68*23
   li    $3,-23
   div   $2,$3
   nop
   mflo  $4
   sub   $4,$0,$4
   sb    $4,0($20)    #D
   li    $2,-69*13
   li    $3,-13
   div   $2,$3
   mflo  $4
   sb    $4,0($20)    #E
   sb    $21,0($20)

   #f: DIVU
   ori   $2,$0,'f'
   sb    $2,0($20)
   ori   $2,$0,65*13
   ori   $3,$0,13
   divu  $2,$3
   nop
   mflo  $4
   sb    $4,0($20)    #A
   sb    $21,0($20)

   #g: MULT
   ori   $2,$0,'g'
   sb    $2,0($20)
   ori   $2,$0,5
   ori   $3,$0,13
   mult  $2,$3
   nop
   mflo  $4
   sb    $4,0($20)    #A
   li    $2,-5
   ori   $3,$0,13
   mult  $2,$3
   nop
   mflo  $4
   sub   $4,$0,$4
   addi  $4,$4,1
   sb    $4,0($20)    #B
   ori   $2,$0,5
   li    $3,-13
   mult  $2,$3
   nop
   mflo  $4
   sub   $4,$0,$4
   addi  $4,$4,2
   sb    $4,0($20)    #C
   li    $2,-5
   li    $3,-13
   mult  $2,$3
   nop
   mflo  $4
   addi  $4,$4,3
   sb    $4,0($20)    #D
   sb    $21,0($20)

   #h: MULTU
   ori   $2,$0,'h'
   sb    $2,0($20)
   ori   $2,$0,5
   ori   $3,$0,13
   multu $2,$3
   nop
   mflo  $4
   sb    $4,0($20)    #A
   sb    $21,0($20)

   #i: SLT
   ori   $2,$0,'i'
   sb    $2,0($20)
   ori   $2,$0,10
   ori   $3,$0,12
   slt   $4,$2,$3
   addi  $5,$4,64
   sb    $5,0($20)    #A
   slt   $4,$3,$2
   addi  $5,$4,66
   sb    $5,0($20)    #B
   li    $2,0xfffffff0
   slt   $4,$2,$3
   addi  $5,$4,66
   sb    $5,0($20)    #C
   slt   $4,$3,$2
   addi  $5,$4,68
   sb    $5,0($20)    #D
   li    $3,0xffffffff
   slt   $4,$2,$3
   addi  $5,$4,68
   sb    $5,0($20)    #E
   slt   $4,$3,$2
   addi  $5,$4,70
   sb    $5,0($20)    #F
   sb    $21,0($20)

   #j: SLTI
   ori   $2,$0,'j'
   sb    $2,0($20)
   ori   $2,$0,10
   slti  $4,$2,12
   addi  $5,$4,64
   sb    $5,0($20)    #A
   slti  $4,$2,8
   addi  $5,$4,66
   sb    $5,0($20)    #B
   sb    $21,0($20)

   #k: SLTIU
   ori   $2,$0,'k'
   sb    $2,0($20)
   ori   $2,$0,10
   sltiu $4,$2,12
   addi  $5,$4,64
   sb    $5,0($20)    #A
   sltiu $4,$2,8
   addi  $5,$4,66
   sb    $5,0($20)    #B
   sb    $21,0($20)

   #l: SLTU
   ori   $2,$0,'l'
   sb    $2,0($20)
   ori   $2,$0,10
   ori   $3,$0,12
   slt   $4,$2,$3
   addi  $5,$4,64
   sb    $5,0($20)    #A
   slt   $4,$3,$2
   addi  $5,$4,66
   sb    $5,0($20)    #B
   sb    $21,0($20)

   #m: SUB
   ori   $2,$0,'m'
   sb    $2,0($20)
   ori   $3,$0,70
   ori   $4,$0,5
   sub   $2,$3,$4
   sb    $2,0($20)    #A
   sb    $21,0($20)

   #n: SUBU
   ori   $2,$0,'n'
   sb    $2,0($20)
   ori   $3,$0,70
   ori   $4,$0,5
   sub   $2,$3,$4
   sb    $2,0($20)    #A
   sb    $21,0($20)

   ######################################
   #Branch and Jump Instructions
   ######################################
   ori   $2,$0,'B'
   sb    $2,0($20)
   ori   $2,$0,'r'
   sb    $2,0($20)
   ori   $2,$0,'a'
   sb    $2,0($20)
   ori   $2,$0,'n'
   sb    $2,0($20)
   ori   $2,$0,'c'
   sb    $2,0($20)
   ori   $2,$0,'h'
   sb    $2,0($20)
   sb    $21,0($20)

   #a: B
   ori   $2,$0,'a'
   sb    $2,0($20)
   ori   $10,$0,'A'
   ori   $11,$0,'B'
   b     $B1
   sb    $10,0($20)
   sb    $22,0($20)
$B1:
   sb    $11,0($20)
   sb    $21,0($20)

   #b: BAL
   ori   $2,$0,'b'
   sb    $2,0($20)
   ori   $10,$0,'A'
   ori   $11,$0,'B'
   ori   $12,$0,'C'
   ori   $13,$0,'D'
   ori   $14,$0,'E'
   ori   $15,$0,'X'
   bal   $BAL1
   sb    $10,0($20)
   sb    $13,0($20)
   b     $BAL2
   sb    $14,0($20)
   sb    $15,0($20)
$BAL1:
   sb    $11,0($20)
   jr    $31
   sb    $12,0($20)
   sb    $22,0($20)
$BAL2:
   sb    $21,0($20)

   #c: BEQ
   ori   $2,$0,'c'
   sb    $2,0($20)
   ori   $10,$0,'A'
   ori   $11,$0,'B'
   ori   $12,$0,'C'
   ori   $13,$0,'D'
   ori   $2,$0,100
   ori   $3,$0,123
   ori   $4,$0,123
   beq   $2,$3,$BEQ1
   sb    $10,0($20)
   sb    $11,0($20)
   beq   $3,$4,$BEQ1
   sb    $12,0($20)
   sb    $22,0($20)
$BEQ1:
   sb    $13,0($20)
   sb    $21,0($20)

   #d: BGEZ
   ori   $2,$0,'d'
   sb    $2,0($20)
   ori   $10,$0,'A'
   ori   $11,$0,'B'
   ori   $12,$0,'C'
   ori   $13,$0,'D'
   or    $15,$0,'X'
   ori   $2,$0,100
   li    $3,0xffff1234
   ori   $4,$0,123
   bgez  $3,$BGEZ1
   sb    $10,0($20)
   sb    $11,0($20)
   bgez  $2,$BGEZ1
   sb    $12,0($20)
   sb    $22,0($20)
$BGEZ1:
   bgez  $0,$BGEZ2
   nop
   sb    $15,0($20)
$BGEZ2:
   sb    $13,0($20)
   sb    $21,0($20)

   #e: BGEZAL
   ori   $2,$0,'e'
   sb    $2,0($20)
   ori   $10,$0,'A'
   ori   $11,$0,'B'
   ori   $12,$0,'C'
   ori   $13,$0,'D'
   ori   $14,$0,'E'
   ori   $15,$0,'X'
   li    $3,0xffff1234
   bgezal $3,$BGEZAL1
   nop
   sb    $10,0($20)
   bgezal $0,$BGEZAL1
   nop
   sb    $13,0($20)
   b     $BGEZAL2
   sb    $14,0($20)
   sb    $15,0($20)
$BGEZAL1:
   sb    $11,0($20)
   jr    $31
   sb    $12,0($20)
   sb    $22,0($20)
$BGEZAL2:
   sb    $21,0($20)

   #f: BGTZ
   ori   $2,$0,'f'
   sb    $2,0($20)
   ori   $10,$0,'A'
   ori   $11,$0,'B'
   ori   $12,$0,'C'
   ori   $13,$0,'D'
   ori   $2,$0,100
   li    $3,0xffff1234
   bgtz  $3,$BGTZ1
   sb    $10,0($20)
   sb    $11,0($20)
   bgtz  $2,$BGTZ1
   sb    $12,0($20)
   sb    $22,0($20)
$BGTZ1:
   sb    $13,0($20)
   sb    $21,0($20)

   #g: BLEZ
   ori   $2,$0,'g'
   sb    $2,0($20)
   ori   $10,$0,'A'
   ori   $11,$0,'B'
   ori   $12,$0,'C'
   ori   $13,$0,'D'
   ori   $2,$0,100
   li    $3,0xffff1234
   blez  $2,$BLEZ1
   sb    $10,0($20)
   sb    $11,0($20)
   blez  $3,$BLEZ1
   sb    $12,0($20)
   sb    $22,0($20)
$BLEZ1:
   blez  $0,$BLEZ2
   nop
   sb    $22,0($20)
$BLEZ2:
   sb    $13,0($20)
   sb    $21,0($20)

   #h: BLTZ
   ori   $2,$0,'h'
   sb    $2,0($20)
   ori   $10,$0,'A'
   ori   $11,$0,'B'
   ori   $12,$0,'C'
   ori   $13,$0,'D'
   ori   $14,$0,'E'
   ori   $2,$0,100
   li    $3,0xffff1234
   ori   $4,$0,0
   bltz  $2,$BLTZ1
   sb    $10,0($20)
   sb    $11,0($20)
   bltz  $3,$BLTZ1
   sb    $12,0($20)
   sb    $22,0($20)
$BLTZ1:
   bltz  $4,$BLTZ2
   nop
   sb    $13,0($20)
$BLTZ2:
   sb    $14,0($20)
   sb    $21,0($20)

   #i: BLTZAL
   ori   $2,$0,'i'
   sb    $2,0($20)
   ori   $10,$0,'A'
   ori   $11,$0,'B'
   ori   $12,$0,'C'
   ori   $13,$0,'D'
   ori   $14,$0,'E'
   ori   $15,$0,'X'
   li    $3,0xffff1234
   bltzal $0,$BLTZAL1
   nop
   sb    $10,0($20)
   bltzal $3,$BLTZAL1
   nop
   sb    $13,0($20)
   b     $BLTZAL2
   sb    $14,0($20)
   sb    $15,0($20)
$BLTZAL1:
   sb    $11,0($20)
   jr    $31
   sb    $12,0($20)
   sb    $22,0($20)
$BLTZAL2:
   sb    $21,0($20)

   #j: BNE
   ori   $2,$0,'j'
   sb    $2,0($20)
   ori   $10,$0,'A'
   ori   $11,$0,'B'
   ori   $12,$0,'C'
   ori   $13,$0,'D'
   ori   $2,$0,100
   ori   $3,$0,123
   ori   $4,$0,123
   bne   $3,$4,$BNE1
   sb    $10,0($20)
   sb    $11,0($20)
   bne   $2,$3,$BNE1
   sb    $12,0($20)
   sb    $22,0($20)
$BNE1:
   sb    $13,0($20)
   sb    $21,0($20)

   #k: J
   ori   $2,$0,'k'
   sb    $2,0($20)
   ori   $10,$0,'A'
   ori   $11,$0,'B'
   ori   $15,$0,'X'
   j     $J1
   sb    $10,0($20)
   sb    $15,0($20)
$J1:
   sb    $11,0($20)
   sb    $21,0($20)

   #l: JAL
   ori   $2,$0,'l'
   sb    $2,0($20)
   ori   $10,$0,'A'
   ori   $11,$0,'B'
   ori   $12,$0,'C'
   ori   $13,$0,'D'
   ori   $14,$0,'E'
   ori   $15,$0,'X'
   jal   $JAL1
   sb    $10,0($20)
   sb    $13,0($20)
   b     $JAL2
   sb    $14,0($20)
   sb    $15,0($20)
$JAL1:
   sb    $11,0($20)
   jr    $31
   sb    $12,0($20)
   sb    $22,0($20)
$JAL2:
   sb    $21,0($20)

   #m: JALR
   ori   $2,$0,'m'
   sb    $2,0($20)
   ori   $10,$0,'A'
   ori   $11,$0,'B'
   ori   $12,$0,'C'
   ori   $13,$0,'D'
   ori   $14,$0,'E'
   ori   $15,$0,'X'
   la    $3,$JALR1
   jalr  $3
   sb    $10,0($20)
   sb    $13,0($20)
   b     $JALR2
   sb    $14,0($20)
   sb    $15,0($20)
$JALR1:
   sb    $11,0($20)
   jr    $31
   sb    $12,0($20)
   sb    $22,0($20)
$JALR2:
   sb    $21,0($20)

   #n: JR
   ori   $2,$0,'n'
   sb    $2,0($20)
   ori   $10,$0,'A'
   ori   $11,$0,'B'
   ori   $15,$0,'X'
   la    $3,$JR1
   jr    $3
   sb    $10,0($20)
   sb    $15,0($20)
$JR1:
   sb    $11,0($20)
   sb    $21,0($20)

   #o: NOP
   ori   $2,$0,'o'
   sb    $2,0($20)
   ori   $2,$0,65
   nop
   sb    $2,0($20)
   sb    $21,0($20)

 
   ######################################
   #Load, Store, and Memory Control Instructions
   ######################################
   ori   $2,$0,'L'
   sb    $2,0($20)
   ori   $2,$0,'o'
   sb    $2,0($20)
   ori   $2,$0,'a'
   sb    $2,0($20)
   ori   $2,$0,'d'
   sb    $2,0($20)
   sb    $21,0($20)

   #a: LB
   ori   $2,$0,'a'
   sb    $2,0($20)
   ori   $2,$0,0xf000
   li    $3,0x41424344
   sw    $3,16($2)
   lb    $4,16($2)
   sb    $4,0($20)
   lb    $4,17($2)
   sb    $4,0($20)
   lb    $4,18($2)
   sb    $4,0($20)
   lb    $2,19($2)
   sb    $2,0($20)
   sb    $21,0($20)

   #b: LBU
   ori   $2,$0,'b'
   sb    $2,0($20)
   ori   $2,$0,0xf000
   li    $3,0x41424344
   sw    $3,16($2)
   lb    $4,16($2)
   sb    $4,0($20)
   lb    $4,17($2)
   sb    $4,0($20)
   lb    $4,18($2)
   sb    $4,0($20)
   lb    $2,19($2)
   sb    $2,0($20)
   sb    $21,0($20)

   #c: LH
   ori   $2,$0,'c'
   sb    $2,0($20)
   ori   $2,$0,0xf000
   li    $3,0x00410042
   sw    $3,16($2)
   lh    $4,16($2)
   sb    $4,0($20)
   lh    $2,18($2)
   sb    $2,0($20)
   sb    $21,0($20)

   #d: LHU
   ori   $2,$0,'d'
   sb    $2,0($20)
   ori   $2,$0,0xf000
   li    $3,0x00410042
   sw    $3,16($2)
   lh    $4,16($2)
   sb    $4,0($20)
   lh    $2,18($2)
   sb    $2,0($20)
   sb    $21,0($20)

   #e: LW
   ori   $2,$0,'e'
   sb    $2,0($20)
   ori   $2,$0,0xf000
   li    $3,'A'
   sw    $3,16($2)
   ori   $3,$0,0
   lw    $2,16($2)
   sb    $2,0($20)
   sb    $21,0($20)

   #f: LWL & LWR
   ori   $2,$0,'f'
   sb    $2,0($20)
   ori   $2,$0,0xf000
   li    $3,'A'
   sw    $3,16($2)
   ori   $3,$0,0
   lwl   $2,16($2)
   lwr   $2,16($2)
   sb    $2,0($20)
   sb    $21,0($20)

   #g: SB
   ori   $2,$0,'g'
   sb    $2,0($20)
   ori   $2,$0,'A'
   sb    $2,0($20)
   sb    $21,0($20)

   #h: SH
   ori   $2,$0,'h'
   sb    $2,0($20)
   ori   $4,$0,0xf000
   ori   $2,$0,0x4142
   sh    $2,16($4)
   lb    $3,16($4)
   sb    $3,0($20)
   lb    $2,17($4)
   sb    $2,0($20)
   sb    $21,0($20)

   #i: SW
   ori   $2,$0,'i'
   sb    $2,0($20)
   ori   $2,$0,0xf000
   li    $3,0x41424344
   sw    $3,16($2)
   lb    $4,16($2)
   sb    $4,0($20)
   lb    $4,17($2)
   sb    $4,0($20)
   lb    $4,18($2)
   sb    $4,0($20)
   lb    $2,19($2)
   sb    $2,0($20)
   sb    $21,0($20)

   #j: SWL & SWR
   ori   $2,$0,'j'
   sb    $2,0($20)
   ori   $2,$0,0xf000
   li    $3,0x41424344
   swl   $3,16($2)
   swr   $3,16($2)
   lb    $4,16($2)
   sb    $4,0($20)
   lb    $4,17($2)
   sb    $4,0($20)
   lb    $4,18($2)
   sb    $4,0($20)
   lb    $2,19($2)
   sb    $2,0($20)
   sb    $21,0($20)


   ######################################
   #Logical Instructions
   ######################################
   ori   $2,$0,'L'
   sb    $2,0($20)
   ori   $2,$0,'o'
   sb    $2,0($20)
   ori   $2,$0,'g'
   sb    $2,0($20)
   ori   $2,$0,'i'
   sb    $2,0($20)
   ori   $2,$0,'c'
   sb    $2,0($20)
   sb    $21,0($20)

   #a: AND
   ori   $2,$0,'a'
   sb    $2,0($20)
   ori   $2,$0,0x0741
   ori   $3,$0,0x60f3
   and   $4,$2,$3
   sb    $4,0($20)
   sb    $21,0($20)

   #b: ANDI
   ori   $2,$0,'b'
   sb    $2,0($20)
   ori   $2,$0,0x0741
   andi  $4,$2,0x60f3
   sb    $4,0($20)
   sb    $21,0($20)

   #c: LUI
   ori   $2,$0,'c'
   sb    $2,0($20)
   lui   $2,0x41
   srl   $3,$2,16
   sb    $3,0($20)
   sb    $21,0($20)

   #d: NOR
   ori   $2,$0,'d'
   sb    $2,0($20)
   li    $2,0xf0fff08e
   li    $3,0x0f0f0f30
   nor   $4,$2,$3
   sb    $4,0($20)
   sb    $21,0($20)

   #e: OR
   ori   $2,$0,'e'
   sb    $2,0($20)
   ori   $2,$0,0x40
   ori   $3,$0,0x01
   or    $4,$2,$3
   sb    $4,0($20)
   sb    $21,0($20)

   #f: ORI
   ori   $2,$0,'f'
   sb    $2,0($20)
   ori   $2,$0,0x40
   ori   $4,$2,0x01
   sb    $4,0($20)
   sb    $21,0($20)

   #g: XOR
   ori   $2,$0,'g'
   sb    $2,0($20)
   ori   $2,$0,0xf043
   ori   $3,$0,0xf002
   xor   $4,$2,$3
   sb    $4,0($20)
   sb    $21,0($20)

   #h: XORI
   ori   $2,$0,'h'
   sb    $2,0($20)
   ori   $2,$0,0xf043
   xor   $4,$2,0xf002
   sb    $4,0($20)
   sb    $21,0($20)

 
   ######################################
   #Move Instructions
   ######################################
   ori   $2,$0,'M'
   sb    $2,0($20)
   ori   $2,$0,'o'
   sb    $2,0($20)
   ori   $2,$0,'v'
   sb    $2,0($20)
   ori   $2,$0,'e'
   sb    $2,0($20)
   sb    $21,0($20)

   #a: MFHI
   ori   $2,$0,'a'
   sb    $2,0($20)
   ori   $2,$0,65
   mthi  $2
   mfhi  $3
   sb    $3,0($20)
   sb    $21,0($20)

   #b: MFLO
   ori   $2,$0,'b'
   sb    $2,0($20)
   ori   $2,$0,65
   mtlo  $2
   mflo  $3
   sb    $3,0($20)
   sb    $21,0($20)

   #c: MTHI
   ori   $2,$0,'c'
   sb    $2,0($20)
   ori   $2,$0,65
   mthi  $2
   mfhi  $3
   sb    $3,0($20)
   sb    $21,0($20)

   #d: MTLO
   ori   $2,$0,'d'
   sb    $2,0($20)
   ori   $2,$0,65
   mtlo  $2
   mflo  $3
   sb    $3,0($20)
   sb    $21,0($20)


   ######################################
   #Shift Instructions
   ######################################
   ori   $2,$0,'S'
   sb    $2,0($20)
   ori   $2,$0,'h'
   sb    $2,0($20)
   ori   $2,$0,'i'
   sb    $2,0($20)
   ori   $2,$0,'f'
   sb    $2,0($20)
   ori   $2,$0,'t'
   sb    $2,0($20)
   sb    $21,0($20)

   #a: SLL
   ori   $2,$0,'a'
   sb    $2,0($20)
   li    $2,0x40414243
   sll   $3,$2,8
   srl   $3,$3,24
   sb    $3,0($20)
   sb    $21,0($20)

   #b: SLLV
   ori   $2,$0,'b'
   sb    $2,0($20)
   li    $2,0x40414243
   ori   $3,$0,8
   sllv  $3,$2,$3
   srl   $3,$3,24
   sb    $3,0($20)
   sb    $21,0($20)

   #c: SRA
   ori   $2,$0,'c'
   sb    $2,0($20)
   li    $2,0x40414243
   sra   $3,$2,16
   sb    $3,0($20)
   li    $2,0x84000000
   sra   $3,$2,25
   sub   $3,$3,0x80
   sb    $3,0($20)
   sb    $21,0($20)

   #d: SRAV
   ori   $2,$0,'d'
   sb    $2,0($20)
   li    $2,0x40414243
   ori   $3,$0,16
   srav  $3,$2,$3
   sb    $3,0($20)
   ori   $3,$0,25
   li    $2,0x84000000
   srav  $3,$2,$3
   sub   $3,$3,0x80
   sb    $3,0($20)
   sb    $21,0($20)

   #e: SRL
   ori   $2,$0,'e'
   sb    $2,0($20)
   li    $2,0x40414243
   srl   $3,$2,16
   sb    $3,0($20)
   li    $2,0x84000000
   srl   $3,$2,25
   sb    $3,0($20)
   sb    $21,0($20)

   #f: SRLV
   ori   $2,$0,'f'
   sb    $2,0($20)
   li    $2,0x40414243
   ori   $3,$0,16
   srlv  $4,$2,$3
   sb    $4,0($20)
   ori   $3,$0,25
   li    $2,0x84000000
   srlv  $3,$2,$3
   sb    $3,0($20)
   sb    $21,0($20)


   ori   $2,$0,'D'
   sb    $2,0($20)
   ori   $2,$0,'o'
   sb    $2,0($20)
   ori   $2,$0,'n'
   sb    $2,0($20)
   ori   $2,$0,'e'
   sb    $2,0($20)
   sb    $21,0($20)


$DONE:
   j     $DONE
   nop

   .set reorder
        .end    entry