2018-09-09 23:08:25 +00:00
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#
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.sect .text; .sect .rom; .sect .data; .sect .bss
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/* Loads a variable-sized block onto the stack.
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*
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* On entry: r2 = size
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* Stack: ( address -- block )
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* Preserves r25 for .lar4 and .sar4
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*/
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.sect .text
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.define .los4
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.los4:
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2018-09-17 17:44:17 +00:00
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lw r4, 0(sp) ! r4 = address of source block
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2018-09-09 23:08:25 +00:00
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! Sizes 1 and 2 are handled specially.
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li at, 1
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beq r2, at, byte_sized
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nop
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li at, 2
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beq r2, at, word_sized
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nop
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! Else the size must be a multiple of 4.
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srl r5, r2, 2 ! r5 = number of words
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2018-09-17 17:44:17 +00:00
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addiu sp, sp, 4 ! retract over address
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subu sp, sp, r2 ! allocate space for destination block
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mov r6, sp ! r6 = start of destination block
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2018-09-09 23:08:25 +00:00
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1:
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2018-09-17 17:44:17 +00:00
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lw at, 0(r4)
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2018-09-09 23:08:25 +00:00
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sw at, 0(r6)
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2018-09-17 17:44:17 +00:00
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addiu r4, r4, 4
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2018-09-09 23:08:25 +00:00
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addiu r6, r6, 4
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addiu r5, r5, -1
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bne r5, zero, 1b
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nop
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jr ra
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nop
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byte_sized:
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2018-09-17 17:44:17 +00:00
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lbu at, 0(r4)
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2018-09-09 23:08:25 +00:00
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sw at, 0(sp)
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jr ra
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nop
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word_sized:
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2018-09-17 17:44:17 +00:00
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lhu at, 0(r4)
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2018-09-09 23:08:25 +00:00
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sw at, 0(sp)
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jr ra
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nop
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