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cc65/libsrc/apple2/cgetc.s

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New version from Oliver Schmidt git-svn-id: svn://svn.cc65.org/cc65/trunk@3421 b7a2c559-68d2-44c3-8de9-860c34a00d81
2005-03-26 17:03:30 +00:00
;
; Kevin Ruland
;
; char cgetc (void);
;
; If open_apple key is pressed then the high-bit of the key is set.
;
This commit was generated by cvs2svn to compensate for changes in r2, which included commits to RCS files with non-trunk default branches. git-svn-id: svn://svn.cc65.org/cc65/trunk@3 b7a2c559-68d2-44c3-8de9-860c34a00d81
2000-05-28 13:40:48 +00:00
Added CONIO cursor support. For quite some time I deliberately didn't add cursor support to the Apple II CONIO imöplementation. I consider it inappropriate to increase the size of cgetc() unduly for a rather seldom used feature. There's no hardware cursor on the Apple II so displaying a cursor during keyboard input means reading the character stored at the cursor location, writing the cursor character, reading the keyboard and finally writing back the character read initially. The naive approach is to reuse the part of cputc() that determines the memory location of the character at the cursor position in order to read the character stored there. However that means to add at least one additional JSR / RTS pair to cputc() adding 4 bytes and 12 cycles :-( Apart from that this approach means still a "too" large cgetc(). The approach implemented instead is to include all functionality required by cgetc() into cputc() - which is to read the current character before writing a new one. This may seem surprising at first glance but an LDA(),Y / TAX sequence adds only 3 bytes and 7 cycles so it cheaper than the JSR / RTS pair and allows to brings down the code increase in cgetc() down to a reasonable value. However so far the internal cputc() code in question saved the X register. Now it uses the X register to return the old character present before writing the new character for cgetc(). This requires some rather small adjustments in other functions using that internal cputc() code.
2016-06-19 13:03:20 +00:00
.export _cgetc
.import cursor, putchardirect
New version from Oliver Schmidt git-svn-id: svn://svn.cc65.org/cc65/trunk@3421 b7a2c559-68d2-44c3-8de9-860c34a00d81
2005-03-26 17:03:30 +00:00
Added CONIO cursor support. For quite some time I deliberately didn't add cursor support to the Apple II CONIO imöplementation. I consider it inappropriate to increase the size of cgetc() unduly for a rather seldom used feature. There's no hardware cursor on the Apple II so displaying a cursor during keyboard input means reading the character stored at the cursor location, writing the cursor character, reading the keyboard and finally writing back the character read initially. The naive approach is to reuse the part of cputc() that determines the memory location of the character at the cursor position in order to read the character stored there. However that means to add at least one additional JSR / RTS pair to cputc() adding 4 bytes and 12 cycles :-( Apart from that this approach means still a "too" large cgetc(). The approach implemented instead is to include all functionality required by cgetc() into cputc() - which is to read the current character before writing a new one. This may seem surprising at first glance but an LDA(),Y / TAX sequence adds only 3 bytes and 7 cycles so it cheaper than the JSR / RTS pair and allows to brings down the code increase in cgetc() down to a reasonable value. However so far the internal cputc() code in question saved the X register. Now it uses the X register to return the old character present before writing the new character for cgetc(). This requires some rather small adjustments in other functions using that internal cputc() code.
2016-06-19 13:03:20 +00:00
.include "apple2.inc"
This commit was generated by cvs2svn to compensate for changes in r2, which included commits to RCS files with non-trunk default branches. git-svn-id: svn://svn.cc65.org/cc65/trunk@3 b7a2c559-68d2-44c3-8de9-860c34a00d81
2000-05-28 13:40:48 +00:00
_cgetc:
Added CONIO cursor support. For quite some time I deliberately didn't add cursor support to the Apple II CONIO imöplementation. I consider it inappropriate to increase the size of cgetc() unduly for a rather seldom used feature. There's no hardware cursor on the Apple II so displaying a cursor during keyboard input means reading the character stored at the cursor location, writing the cursor character, reading the keyboard and finally writing back the character read initially. The naive approach is to reuse the part of cputc() that determines the memory location of the character at the cursor position in order to read the character stored there. However that means to add at least one additional JSR / RTS pair to cputc() adding 4 bytes and 12 cycles :-( Apart from that this approach means still a "too" large cgetc(). The approach implemented instead is to include all functionality required by cgetc() into cputc() - which is to read the current character before writing a new one. This may seem surprising at first glance but an LDA(),Y / TAX sequence adds only 3 bytes and 7 cycles so it cheaper than the JSR / RTS pair and allows to brings down the code increase in cgetc() down to a reasonable value. However so far the internal cputc() code in question saved the X register. Now it uses the X register to return the old character present before writing the new character for cgetc(). This requires some rather small adjustments in other functions using that internal cputc() code.
2016-06-19 13:03:20 +00:00
; Cursor on ?
lda cursor
beq :+
New version from Oliver Schmidt git-svn-id: svn://svn.cc65.org/cc65/trunk@3421 b7a2c559-68d2-44c3-8de9-860c34a00d81
2005-03-26 17:03:30 +00:00
Added CONIO cursor support. For quite some time I deliberately didn't add cursor support to the Apple II CONIO imöplementation. I consider it inappropriate to increase the size of cgetc() unduly for a rather seldom used feature. There's no hardware cursor on the Apple II so displaying a cursor during keyboard input means reading the character stored at the cursor location, writing the cursor character, reading the keyboard and finally writing back the character read initially. The naive approach is to reuse the part of cputc() that determines the memory location of the character at the cursor position in order to read the character stored there. However that means to add at least one additional JSR / RTS pair to cputc() adding 4 bytes and 12 cycles :-( Apart from that this approach means still a "too" large cgetc(). The approach implemented instead is to include all functionality required by cgetc() into cputc() - which is to read the current character before writing a new one. This may seem surprising at first glance but an LDA(),Y / TAX sequence adds only 3 bytes and 7 cycles so it cheaper than the JSR / RTS pair and allows to brings down the code increase in cgetc() down to a reasonable value. However so far the internal cputc() code in question saved the X register. Now it uses the X register to return the old character present before writing the new character for cgetc(). This requires some rather small adjustments in other functions using that internal cputc() code.
2016-06-19 13:03:20 +00:00
; Show caret.
.ifdef __APPLE2ENH__
lda #$7F | $80 ; Checkerboard, screen code
.else
lda #' ' | $40 ; Blank, flashing
.endif
jsr putchardirect ; Returns old character in X
; Wait for keyboard strobe.
: lda KBD
bpl :- ; If < 128, no key pressed
; Cursor on ?
ldy cursor
beq :+
; Restore old character.
pha
txa
jsr putchardirect
pla
; At this time, the high bit of the key pressed is set.
: bit KBDSTRB ; Clear keyboard strobe
New cgetc with apple2enh fix from Oliver Scmidt git-svn-id: svn://svn.cc65.org/cc65/trunk@3454 b7a2c559-68d2-44c3-8de9-860c34a00d81
2005-04-08 19:27:07 +00:00
.ifdef __APPLE2ENH__
Removed (pretty inconsistently used) tab chars from source code base.
2013-05-09 11:56:54 +00:00
bit BUTN0 ; Check if OpenApple is down
New cgetc with apple2enh fix from Oliver Scmidt git-svn-id: svn://svn.cc65.org/cc65/trunk@3454 b7a2c559-68d2-44c3-8de9-860c34a00d81
2005-04-08 19:27:07 +00:00
bmi done
.endif
Removed (pretty inconsistently used) tab chars from source code base.
2013-05-09 11:56:54 +00:00
and #$7F ; If not down, then clear high bit
Added CONIO cursor support. For quite some time I deliberately didn't add cursor support to the Apple II CONIO imöplementation. I consider it inappropriate to increase the size of cgetc() unduly for a rather seldom used feature. There's no hardware cursor on the Apple II so displaying a cursor during keyboard input means reading the character stored at the cursor location, writing the cursor character, reading the keyboard and finally writing back the character read initially. The naive approach is to reuse the part of cputc() that determines the memory location of the character at the cursor position in order to read the character stored there. However that means to add at least one additional JSR / RTS pair to cputc() adding 4 bytes and 12 cycles :-( Apart from that this approach means still a "too" large cgetc(). The approach implemented instead is to include all functionality required by cgetc() into cputc() - which is to read the current character before writing a new one. This may seem surprising at first glance but an LDA(),Y / TAX sequence adds only 3 bytes and 7 cycles so it cheaper than the JSR / RTS pair and allows to brings down the code increase in cgetc() down to a reasonable value. However so far the internal cputc() code in question saved the X register. Now it uses the X register to return the old character present before writing the new character for cgetc(). This requires some rather small adjustments in other functions using that internal cputc() code.
2016-06-19 13:03:20 +00:00
done: ldx #>$0000
New version from Oliver Schmidt git-svn-id: svn://svn.cc65.org/cc65/trunk@3421 b7a2c559-68d2-44c3-8de9-860c34a00d81
2005-03-26 17:03:30 +00:00
rts
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