72 lines
1.7 KiB
ArmAsm
72 lines
1.7 KiB
ArmAsm
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.export boot_end
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.export lowmem
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decrunch_p2o=decrunch_end-decrunch_dst-256 ; offset to start of second page to copy
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boot_end=decrunch_src+decrunch_end-decrunch_dst
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boot_length=boot_end-$0801
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boot_start=$0801
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.ifdef NU_SEI
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sei
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.else
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lda#$7f
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sta $dc0d ; kill CIA irq
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.endif
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lda#$34
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sta $01 ;disable roms and IO during decrunch
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ldx#255
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txs
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: lda $0243,x ; save 0x244 to 0x333 to stack. 0x334 to 0x3ff is tape buffer
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sta $0100,x
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dex
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bne :-
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: lda decrunch_src,x
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sta decrunch_dst,x
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lda decrunch_src+decrunch_p2o,x
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sta decrunch_dst+decrunch_p2o,x
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dex
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bne :-
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jmp lowmem
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decrunch_src:
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.org $0244
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decrunch_dst:
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.include "rdecrunch.s"
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lowmem:
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o_frag_copy:
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lda $8000,x
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sta $07e8,x
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lda $8000,x
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sta boot_end-256,x
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dex ; if ever we need this code space back, just recompress this chunk
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bne lowmem ; as the first thing to be decrunched from the stream :D
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o_stream_start:
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ldx#<($1800)
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lda#>($17ff)
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jsr decrunch
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ldy#$f0
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: lda $0100,y
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sta $0243,y ; restore 0x244 to 0x333 from stack
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dey
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bne :-
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o_memory_config:
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lda#$37 ; operand overwitten by patch_and_prepend_boot
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sta $01 ; restore memory config to default
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.ifdef NU_SEI
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cli
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.endif
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o_exec_addr:
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jmp $080d ; destination overwitten by patch_and_prepend_boot
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decrunch_end:
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; patch addresses
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.word o_memory_config - boot_start + decrunch_src - decrunch_dst
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.word o_exec_addr - boot_start + decrunch_src - decrunch_dst
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.word o_stream_start - boot_start + decrunch_src - decrunch_dst
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.word o_frag_copy - boot_start + decrunch_src - decrunch_dst
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