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1d1ba3ed3b
The constructors are _NOT_ allowed anymore to access the BSS. Rather they must use the DATA segment or the INIT segment. The latter isn't cleared at any point so the constructors may use it to expose values to the main program. However they must make sure to always write the values as they are not pre-initialized.
71 lines
1.7 KiB
ArmAsm
71 lines
1.7 KiB
ArmAsm
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; Ullrich von Bassewitz, 06.08.1998
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; char cgetc (void);
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;
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.export _cgetc
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.constructor initcgetc
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.destructor donecgetc
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.import cursor
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.include "c128.inc"
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;--------------------------------------------------------------------------
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_cgetc: lda KEY_COUNT ; Get number of characters
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bne L2 ; Jump if there are already chars waiting
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; Switch on the cursor if needed. We MUST always switch the cursor on,
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; before switching it off, because switching it off will restore the
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; character attribute remembered when it was switched on. So just switching
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; it off will restore the wrong character attribute.
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jsr CURS_SET ; Set cursor to current position
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jsr CURS_ON
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lda cursor
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bne L1
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lda #$01
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jsr CURS_OFF
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L1: lda KEY_COUNT ; Check characters again
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beq L1
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jsr CURS_OFF ; Switch cursor off, if characters available
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L2: jsr KBDREAD ; Read char and return in A
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ldx #0
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rts
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;--------------------------------------------------------------------------
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; Module constructor/destructor
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.segment "INIT"
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keyvec: .res 2
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.segment "ONCE"
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initcgetc:
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; Save the old vector
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lda KeyStoreVec
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ldx KeyStoreVec+1
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sta keyvec
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stx keyvec+1
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; Set the new vector. I can only hope that this works for other C128
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; versions...
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lda #<$C6B7
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ldx #>$C6B7
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jmp SetVec
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.code
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donecgetc:
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lda keyvec
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ldx keyvec+1
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SetVec: sei
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sta KeyStoreVec
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stx KeyStoreVec+1
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cli
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rts
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