CINT should be complete now
This commit is contained in:
FeralChild64 committed
1 parent
a9d167810b
commit
98860e9831
9 files changed
+88
-77
No files matched your search
+2
-52
@@ -1,62 +1,12 @@
|
||||
|
||||
//
|
||||
// It seems this is a part CINT which initializes screen and keyboard, but does not
|
||||
// reset VIC-II. See here: https://csdb.dk/forums/index.php?roomid=11&topicid=17048&firstpost=22
|
||||
// This is a part CINT which initializes screen and keyboard
|
||||
//
|
||||
// For more details see:
|
||||
// - [RG64] C64 Programmer's Reference Guide - page 280
|
||||
// - [CM64] Compute's Mapping the Commodore 64 - page 242
|
||||
|
||||
cint_screen_keyboard_real:
|
||||
|
||||
// XXX check what really is performed here
|
||||
|
||||
// According to [CM64], this routine checks for PAL/NTSC. It's definitely not done
|
||||
// within the 'BRK' part, this can be easily checked - POKE something
|
||||
// to address 678 on a real C64, press STOP+RESTORE, the value won't change
|
||||
|
||||
// Detect video system (PAL/NTSC), use Graham's method, as it's short and reliable
|
||||
// see here: https://codebase64.org/doku.php?id=base:detect_pal_ntsc
|
||||
|
||||
lda #$C8 // preparation, as the VIC might be uninitialized
|
||||
sta VIC_SCROLX
|
||||
|
||||
cint_w0:
|
||||
lda VIC_RASTER
|
||||
cint_w1:
|
||||
cmp VIC_RASTER
|
||||
beq cint_w1
|
||||
bmi cint_w0
|
||||
|
||||
// Result in A, if no interrupt happened during the test:
|
||||
// #$37 -> 312 rasterlines, PAL, VIC 6569
|
||||
// #$06 -> 263 rasterlines, NTSC, VIC 6567R8
|
||||
// #$05 -> 262 rasterlines, NTSC, VIC 6567R56A
|
||||
|
||||
cmp #$07
|
||||
bcs cint_pal
|
||||
|
||||
cint_ntsc:
|
||||
|
||||
// NTSC C64 (https://codebase64.org/doku.php?id=base:cpu_clocking),
|
||||
// is clocked at 1.022727 MHz, so that 1/60s is 17045 CPU cycles
|
||||
|
||||
ldy #<17045
|
||||
ldx #>17045
|
||||
|
||||
sty CIA1_TIMALO
|
||||
stx CIA1_TIMAHI
|
||||
|
||||
lda #$00
|
||||
beq !+
|
||||
|
||||
cint_pal:
|
||||
|
||||
lda #$01
|
||||
!:
|
||||
sta TVSFLG
|
||||
|
||||
cint_brk: // entry for BRK and STOP+RESTORE - XXX, where should it start?
|
||||
cint_screen_keyboard:
|
||||
|
||||
// Setup KEYLOG vector
|
||||
|
||||
@@ -0,0 +1,22 @@
|
||||
|
||||
//
|
||||
// Part of the official Kernal routine, described in:
|
||||
//
|
||||
// - [RG64] C64 Programmer's Reference Guide - page 280
|
||||
// - [CM64] Compute's Mapping the Commodore 64 - page 242
|
||||
//
|
||||
// CPU registers that has to be preserved (see [RG64]): none
|
||||
//
|
||||
|
||||
|
||||
cint_legacy: // $E518
|
||||
|
||||
// Setup video and I/O
|
||||
// See here: https://csdb.dk/forums/index.php?roomid=11&topicid=17048&firstpost=22
|
||||
jsr setup_vicii
|
||||
|
||||
// Code below must be placed under $E51B, or some code will break - see here:
|
||||
// - https://csdb.dk/forums/index.php?roomid=11&topicid=17048&firstpost=2
|
||||
// Game 'Operacja Proboszcz' is one example.
|
||||
|
||||
jmp cint_screen_keyboard // XXX try to fit the code here
|
||||
@@ -0,0 +1,3 @@
|
||||
|
||||
Game 'Operacja Proboszcz' explicitly calls $E51B - thus, it is sane
|
||||
to place old CINT routine in it's original place
|
||||
@@ -1,6 +0,0 @@
|
||||
|
||||
// Routine too long to fit here
|
||||
|
||||
cint_screen_keyboard:
|
||||
|
||||
jmp cint_screen_keyboard_real
|
||||
@@ -1,2 +0,0 @@
|
||||
|
||||
Game 'Operacja Proboszcz' explicitly calls this location.
|
||||
@@ -77,17 +77,16 @@ IOINIT:
|
||||
|
||||
// Set timer interval to ~1/60th of a second
|
||||
|
||||
// (This value was calculated by running a custom IRQ handler on a C64
|
||||
// with original KERNAL, and writing the values of $DC04/5 to the screen
|
||||
// in the IRQ handler to see roughly what value the timers must be set to)
|
||||
// ldy #<16380
|
||||
// ldx #>16380
|
||||
// Probably NTSC is the default one, as PAL support was introduced later,
|
||||
// in a patch - see [CM64] page 242 and page:
|
||||
// - http://commodore64.se/wiki/index.php/Commodore_64_KERNAL_ROM_versions
|
||||
// "The KERNAL ROM R1 was obviously used only in early NTSC systems. It lacks the PAL/NTSC detection"
|
||||
|
||||
// PAL C64 (https://codebase64.org/doku.php?id=base:cpu_clocking),
|
||||
// is clocked at 0.985248 MHz, so that 1/60s is 16421 CPU cycles
|
||||
// NTSC C64 (https://codebase64.org/doku.php?id=base:cpu_clocking),
|
||||
// is clocked at 1.022727 MHz, so that 1/60s is 17045 CPU cycles
|
||||
|
||||
ldy #<16421
|
||||
ldx #>16421
|
||||
ldy #<17045
|
||||
ldx #>17045
|
||||
|
||||
sty CIA1_TIMALO
|
||||
stx CIA1_TIMAHI
|
||||
|
||||
@@ -10,7 +10,47 @@
|
||||
|
||||
CINT:
|
||||
|
||||
// Setup video and I/O
|
||||
jsr setup_vicii
|
||||
jsr cint_legacy
|
||||
|
||||
jmp cint_screen_keyboard
|
||||
cint_check_pal_ntsc:
|
||||
|
||||
// Detect video system (PAL/NTSC), use Graham's method, as it's short and reliable
|
||||
// see here: https://codebase64.org/doku.php?id=base:detect_pal_ntsc
|
||||
|
||||
lda VIC_RASTER
|
||||
!:
|
||||
cmp VIC_RASTER
|
||||
beq !-
|
||||
bmi cint_check_pal_ntsc
|
||||
|
||||
// Result in A, if no interrupt happened during the test:
|
||||
// #$37 -> 312 rasterlines, PAL, VIC 6569
|
||||
// #$06 -> 263 rasterlines, NTSC, VIC 6567R8
|
||||
// #$05 -> 262 rasterlines, NTSC, VIC 6567R56A
|
||||
|
||||
cmp #$07
|
||||
bcc cont_done
|
||||
|
||||
cint_pal:
|
||||
|
||||
// (This value was calculated by running a custom IRQ handler on a C64
|
||||
// with original KERNAL, and writing the values of $DC04/5 to the screen
|
||||
// in the IRQ handler to see roughly what value the timers must be set to)
|
||||
// ldy #<16380
|
||||
// ldx #>16380
|
||||
|
||||
// PAL C64 (https://codebase64.org/doku.php?id=base:cpu_clocking),
|
||||
// is clocked at 0.985248 MHz, so that 1/60s is 16421 CPU cycles
|
||||
|
||||
ldy #<16421
|
||||
ldx #>16421
|
||||
|
||||
sty CIA1_TIMALO
|
||||
stx CIA1_TIMAHI
|
||||
|
||||
lda #$01
|
||||
!:
|
||||
sta TVSFLG
|
||||
|
||||
cont_done:
|
||||
rts
|
||||
Reference in new issue
Block a user