67 lines
947 B
ArmAsm
67 lines
947 B
ArmAsm
.define .inn
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.sect .text
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.sect .rom
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.sect .data
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.sect .bss
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.sect .text
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! Any size bit test on set.
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! Expects in de-reg: size of set (in bytes)
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! Expects on stack: bit number
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! set to be tested
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! Yields in de-reg.: 0 if bit is reset or bit number out of range
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! 1 if bit is set
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.inn: pop h
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shld .retadr
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mov h,b
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mov l,c
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shld .bcreg
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pop h
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xchg !hl = size, de = bit number
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mov a,d !test if bit number is negative
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ral
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jc 3f
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mov a,e
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ani 7
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mov b,a !save bits 0-2 of bit number in b-reg
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mvi c,3
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1: xra a
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mov a,d !shift bit number right 3 times
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rar
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mov d,a
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mov a,e
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rar
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mov e,a
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dcr c
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jnz 1b
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mov a,l !test if bit number is small enough
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sub e
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mov a,h
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sbb d
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jc 3f
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xchg
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dad sp
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xchg
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ldax d !a-register = wanted byte
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2: dcr b !dcr doesn't affect carry bit
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jm 4f
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rar
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jmp 2b
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3: xra a !return 0 if bit number out of range
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4: ani 1
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mov e,a
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mvi d,0
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dad sp
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sphl
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lhld .bcreg
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mov b,h
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mov c,l
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lhld .retadr
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pchl
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