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04cc463452
Please refer to https://github.com/cc65/cc65/pull/532 for background info.
I wrote in https://sourceforge.net/p/cc65/mailman/message/35873183/
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cputs() wraps to the next line if the strings is too long to fit in the current line. I don't know if it's worth the effort to allow cpeeks() to continue reading from the next line. I'd like to discuss this aspect with the actual implementers.
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This is still as unclear today as it was when I wrote the above. Therefore this change just doesn't add cpeeks() at all.
Since f8c6c58373 the Apple II CONIO implementation doesn't "need" revers() anymore - meaning that (nearly) every possible value can be placed in VRAM with a straight cputc() (without the need for a previous revers(1)).
The implementation of cpeekc() leverages that cputc() ability by always returning the value that can be fed into cputc() without a previous revers(1). Accordingly, cpeekrevers() always returns 0.
So after the sequence revers(1); cputc(x); a cpeekc() will return a value different from x! However, I don't see this behavior braking the cpeekc() contract. I see the cpeekc() contract being defined by the sequence textcolor(cpeekcolor()); revers(cpeekrevers()); cputc(cpeekc()); placing the very same value in VRAM that there was before. And that contract is fulfilled.
29 lines
727 B
ArmAsm
29 lines
727 B
ArmAsm
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; 2020-07-12, Oliver Schmidt
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; char cpeekc (void);
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;
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.export _cpeekc
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.include "apple2.inc"
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_cpeekc:
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ldy CH
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.ifdef __APPLE2ENH__
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bit RD80VID ; In 80 column mode?
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bpl peek ; No, just go ahead
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tya
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lsr ; Div by 2
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tay
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bcs peek ; Odd cols are in main memory
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bit HISCR ; Assume SET80COL
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.endif
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peek: lda (BASL),Y ; Get character
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.ifdef __APPLE2ENH__
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bit LOWSCR ; Doesn't hurt in 40 column mode
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.endif
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eor #$80 ; Invert high bit
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ldx #$00
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rts
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