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libsrc/*/kplot.s: Use cbm_kernal.inc symbols, not hardcoded addrs

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On C64, VIC-20 and Plus/4, the conio library PLOT routine uses direct
calls into the Kernal, including the Kernal PLOT routine that we're
replacing. These were previously hardcoded addresses; we change these
to use the symbols for those routines defined in cbm_kernal.inc. (This
changes no functionality.)

To do this, we need to import cbm_kernal.inc in a namespace so we
don't have a collision between the PLOT that we're defining and the
Kernal definition.

We also add a UPDCRAMPTR symbol (used by kplot for VIC-20 and C64) to
the direct entry kernal routines in in cbm_kernal.inc, and expand the
comments describing what the "direct entry" Kernal routines are.

<greg.king5@verizon.net> (GitHub: greg-king5) came up with this idea
and did initial testing of it.

This has been tested on VICE xvic, x64 and xplus4 emulators with a
program that does a cputs() call (github.com/0cjs/vic20cc65) to
confirm that it works the same way after as it did before.
This commit is contained in:
Curt J. Sampson 2019-10-24 13:46:41 +09:00 committed by greg-king5
parent 9fa90e2265
commit 128991d868
4 changed files with 29 additions and 13 deletions
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12
asminc/cbm_kernal.inc
View File

@ -100,14 +100,26 @@ UDTIM := $FFEA
; ---------------------------------------------------------------------------
; Kernal routines, direct entries
;
; Unlike the above, these are not standard functions with entries in the jump
; table. They do not exist in all Kernals, and where they do the entry point is
; specific to that particular machine and possibly even Kernal version.
;
; This list is not comprehensive: missing items for particular machines
; should be added as needed.
;
; UPDCRAMPTR: Updates the color RAM pointer to match the screen RAM pointer.
;
.if .def(__VIC20__)
CLRSCR := $E55F
KBDREAD := $E5CF
UPDCRAMPTR := $EAB2
.elseif .def(__C64__)
CLRSCR := $E544
KBDREAD := $E5B4
NMIEXIT := $FEBC
UPDCRAMPTR := $EA24
.elseif .def(__C128__)
CLRSCR := $C142
KBDREAD := $C006

11
libsrc/c64/kplot.s
View File

@ -7,15 +7,16 @@
.export PLOT
.scope KERNAL
.include "cbm_kernal.inc"
.endscope
.proc PLOT
bcs @L1
jsr $FFF0 ; Set cursor position
jmp $EA24 ; Set pointer to color RAM
jsr KERNAL::PLOT ; Set cursor position using original ROM PLOT
jmp KERNAL::UPDCRAMPTR ; Set pointer to color RAM to match new cursor position
@L1: jmp $FFF0 ; Get cursor position
@L1: jmp KERNAL::PLOT ; Get cursor position
.endproc

9
libsrc/plus4/kplot.s
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@ -6,16 +6,17 @@
.export PLOT
.scope KERNAL
.include "cbm_kernal.inc"
.endscope
.include "plus4.inc"
.segment "LOWCODE" ; Must go into low memory
.proc PLOT
sta ENABLE_ROM ; Enable the ROM
jsr $FFF0 ; Call the ROM routine
jsr KERNAL::PLOT ; Call the ROM routine
sta ENABLE_RAM ; Switch back to RAM
rts ; Return to caller
.endproc

10
libsrc/vic20/kplot.s
View File

@ -7,14 +7,16 @@
.export PLOT
.scope KERNAL
.include "cbm_kernal.inc"
.endscope
.proc PLOT
bcs @L1
jsr $FFF0 ; Set cursor position
jmp $EAB2 ; Set pointer to color RAM
jsr KERNAL::PLOT ; Set cursor position using original ROM PLOT
jmp KERNAL::UPDCRAMPTR ; Set pointer to color RAM to match new cursor position
@L1: jmp $FFF0 ; Get cursor position
@L1: jmp KERNAL::PLOT ; Get cursor position
.endproc