21 lines
289 B
ArmAsm
21 lines
289 B
ArmAsm
// Return C=1 if a pointer in BASIC memory space is NULL, else C=0
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// X = ZP pointer to check
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peek_pointer_null_check:
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ldy #$00
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jsr peek_under_roms
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cmp #$00
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bne ptr_not_null
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iny
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jsr peek_under_roms
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cmp #$00
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bne ptr_not_null
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// Pointer is NULL
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clc
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rts
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ptr_not_null:
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sec
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rts
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