2018-09-08 21:12:57 +00:00
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#
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.sect .text; .sect .rom; .sect .data; .sect .bss
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/* this is not a subroutine, but just a
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* piece of code that computes the jump-
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* address and jumps to it.
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* traps if resulting address is zero
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*
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* Stack: ( value tableaddr -- )
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*/
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.sect .text
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.define .csb
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.csb:
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lw r4, 0(sp) ! r4 = address of table
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2018-09-13 22:15:43 +00:00
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lw r5, 4(sp) ! r5 = value
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2018-09-08 21:12:57 +00:00
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addiu sp, sp, 8
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lw r6, 0(r4) ! r6 = default target
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lw r7, 4(r4) ! r7 = table count
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2:
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addiu r7, r7, -1 ! decrement count
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bltz r7, 1f ! exit loop if out
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nop
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lw r8, 8(r4) ! candidate value
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beq r8, r5, 3f ! branch if equal
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nop
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addiu r4, r4, 8 ! next entry
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b 2b
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nop
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3:
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/* We found an item in the table. */
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lw r6, 12(r4) ! load jump target
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/* fall through */
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1:
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beq r6, zero, 4f /* trap if null */
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nop
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jr r6 /* otherwise jump */
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nop
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4:
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j .trap_ecase
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nop
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