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[/] [mlite/] [trunk/] [tools/] [boot.asm] - Blame information for rev 350

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1 20 rhoads
##################################################################
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# TITLE: Boot Up Code
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# AUTHOR: Steve Rhoads (rhoadss@yahoo.com)
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# DATE CREATED: 1/12/02
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# FILENAME: boot.asm
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# PROJECT: Plasma CPU core
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# COPYRIGHT: Software placed into the public domain by the author.
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#    Software 'as is' without warranty.  Author liable for nothing.
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# DESCRIPTION:
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#    Initializes the stack pointer and jumps to main().
11 20 rhoads
##################################################################
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   #Reserve 512 bytes for stack
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   .comm InitStack, 512
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15
   .text
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   .align 2
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   .global entry
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   .ent entry
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entry:
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   .set noreorder
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22 239 rhoads
   #These four instructions should be the first instructions.
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   #convert.exe previously initialized $gp, .sbss_start, .bss_end, $sp
24 239 rhoads
   la    $gp, _gp             #initialize global pointer
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   la    $5, __bss_start      #$5 = .sbss_start
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   la    $4, _end             #$2 = .bss_end
27 200 rhoads
   la    $sp, InitStack+488   #initialize stack pointer
28 147 rhoads
 
29 28 rhoads
$BSS_CLEAR:
30 239 rhoads
   sw    $0, 0($5)
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   slt   $3, $5, $4
32 130 rhoads
   bnez  $3, $BSS_CLEAR
33 239 rhoads
   addiu $5, $5, 4
34 28 rhoads
 
35 147 rhoads
   jal   main
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   nop
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$L1:
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   j $L1
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40 147 rhoads
   .end entry
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###################################################
44 110 rhoads
   #address 0x3c
45 239 rhoads
   .global interrupt_service_routine
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   .ent interrupt_service_routine
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interrupt_service_routine:
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   .set noreorder
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   .set noat
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51 147 rhoads
   #Registers $26 and $27 are reserved for the OS
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   #Save all temporary registers
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   #Slots 0($29) through 12($29) reserved for saving a0-a3
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   addi  $29, $29, -104  #adjust sp
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   sw    $1,  16($29)    #at
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   sw    $2,  20($29)    #v0
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   sw    $3,  24($29)    #v1
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   sw    $4,  28($29)    #a0
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   sw    $5,  32($29)    #a1
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   sw    $6,  36($29)    #a2
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   sw    $7,  40($29)    #a3
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   sw    $8,  44($29)    #t0
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   sw    $9,  48($29)    #t1
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   sw    $10, 52($29)    #t2
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   sw    $11, 56($29)    #t3
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   sw    $12, 60($29)    #t4
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   sw    $13, 64($29)    #t5
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   sw    $14, 68($29)    #t6
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   sw    $15, 72($29)    #t7
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   sw    $24, 76($29)    #t8
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   sw    $25, 80($29)    #t9
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   sw    $31, 84($29)    #lr
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   mfc0  $26, $14        #C0_EPC=14 (Exception PC)
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   addi  $26, $26, -4    #Backup one opcode
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   sw    $26, 88($29)    #pc
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   mfhi  $27
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   sw    $27, 92($29)    #hi
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   mflo  $27
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   sw    $27, 96($29)    #lo
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81 177 rhoads
   lui   $6,  0x2000
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   lw    $4,  0x20($6)   #IRQ_STATUS
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   lw    $6,  0x10($6)   #IRQ_MASK
84 194 rhoads
   and   $4,  $4, $6
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   jal   OS_InterruptServiceRoutine
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   addi  $5,  $29, 0
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   #Restore all temporary registers
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   lw    $1,  16($29)    #at
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   lw    $2,  20($29)    #v0
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   lw    $3,  24($29)    #v1
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   lw    $4,  28($29)    #a0
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   lw    $5,  32($29)    #a1
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   lw    $6,  36($29)    #a2
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   lw    $7,  40($29)    #a3
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   lw    $8,  44($29)    #t0
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   lw    $9,  48($29)    #t1
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   lw    $10, 52($29)    #t2
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   lw    $11, 56($29)    #t3
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   lw    $12, 60($29)    #t4
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   lw    $13, 64($29)    #t5
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   lw    $14, 68($29)    #t6
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   lw    $15, 72($29)    #t7
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   lw    $24, 76($29)    #t8
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   lw    $25, 80($29)    #t9
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   lw    $31, 84($29)    #lr
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   lw    $26, 88($29)    #pc
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   lw    $27, 92($29)    #hi
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   mthi  $27
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   lw    $27, 96($29)    #lo
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   mtlo  $27
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   addi  $29, $29, 104   #adjust sp
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isr_return:
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   ori   $27, $0, 0x1    #re-enable interrupts
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   jr    $26
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   mtc0  $27, $12        #STATUS=1; enable interrupts
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   .end interrupt_service_routine
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   .set at
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122
 
123 28 rhoads
###################################################
124 239 rhoads
   .global OS_AsmInterruptEnable
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   .ent OS_AsmInterruptEnable
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OS_AsmInterruptEnable:
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   .set noreorder
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   mfc0  $2, $12
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   jr    $31
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   mtc0  $4, $12            #STATUS=1; enable interrupts
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   #nop
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   .set reorder
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   .end OS_AsmInterruptEnable
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135 28 rhoads
 
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###################################################
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   .global  OS_AsmInterruptInit
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   .ent    OS_AsmInterruptInit
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OS_AsmInterruptInit:
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   .set noreorder
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   #Patch interrupt vector to 0x1000003c
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   la    $5, OS_AsmPatchValue
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   lw    $6, 0($5)
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   sw    $6, 0x3c($0)
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   lw    $6, 4($5)
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   sw    $6, 0x40($0)
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   lw    $6, 8($5)
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   sw    $6, 0x44($0)
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   lw    $6, 12($5)
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   jr    $31
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   sw    $6, 0x48($0)
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OS_AsmPatchValue:
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   #Registers $26 and $27 are reserved for the OS
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   #Code to place at address 0x3c
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   lui   $26, 0x1000
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   ori   $26, $26, 0x3c
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   jr    $26
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   nop
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161 147 rhoads
   .set reorder
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   .end OS_AsmInterruptInit
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164
 
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###################################################
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   .global   setjmp
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   .ent     setjmp
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setjmp:
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   .set noreorder
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   sw    $16, 0($4)   #s0
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   sw    $17, 4($4)   #s1
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   sw    $18, 8($4)   #s2
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   sw    $19, 12($4)  #s3
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   sw    $20, 16($4)  #s4
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   sw    $21, 20($4)  #s5
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   sw    $22, 24($4)  #s6
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   sw    $23, 28($4)  #s7
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   sw    $30, 32($4)  #s8
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   sw    $28, 36($4)  #gp
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   sw    $29, 40($4)  #sp
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   sw    $31, 44($4)  #lr
182 130 rhoads
   jr    $31
183 147 rhoads
   ori   $2,  $0, 0
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185 28 rhoads
   .set reorder
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   .end setjmp
187 28 rhoads
 
188
 
189 37 rhoads
###################################################
190 239 rhoads
   .global   longjmp
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   .ent     longjmp
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longjmp:
193 37 rhoads
   .set noreorder
194 147 rhoads
   lw    $16, 0($4)   #s0
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   lw    $17, 4($4)   #s1
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   lw    $18, 8($4)   #s2
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   lw    $19, 12($4)  #s3
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   lw    $20, 16($4)  #s4
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   lw    $21, 20($4)  #s5
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   lw    $22, 24($4)  #s6
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   lw    $23, 28($4)  #s7
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   lw    $30, 32($4)  #s8
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   lw    $28, 36($4)  #gp
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   lw    $29, 40($4)  #sp
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   lw    $31, 44($4)  #lr
206 130 rhoads
   jr    $31
207 147 rhoads
   ori   $2,  $5, 0
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209 37 rhoads
   .set reorder
210 147 rhoads
   .end longjmp
211 37 rhoads
 
212
 
213 147 rhoads
###################################################
214 239 rhoads
   .global   OS_AsmMult
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   .ent     OS_AsmMult
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OS_AsmMult:
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   .set noreorder
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   multu $4, $5
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   mflo  $2
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   mfhi  $4
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   jr    $31
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   sw    $4, 0($6)
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   .set reorder
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   .end OS_AsmMult
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###################################################
229 239 rhoads
   .global OS_Syscall
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   .ent OS_Syscall
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OS_Syscall:
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   .set noreorder
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   syscall 0
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   jr    $31
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   nop
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   .set reorder
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   .end OS_Syscall
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