diff options
| -rw-r--r-- | README.txt | 9 | ||||
| -rw-r--r-- | rand.s | 50 | ||||
| -rw-r--r-- | taipan.c | 6 |
3 files changed, 47 insertions, 18 deletions
@@ -132,10 +132,8 @@ Bugs! At least these: - When exiting to DOS and reloading, the title screen graphics are messed up. The playtester who reported this was running on real - hardware (not an emulator). - -- After a battle, the prices don't get reset (or, not always?) when - entering the new port. + hardware (not an emulator). I can't see how this is happening, but I + expect it's related to this: - The BSS overlaps the start of the title screen. Consequences: There is a momentary graphics glitch when the main game is done loading and @@ -143,6 +141,9 @@ Bugs! At least these: and display the title screen (but that's not something really necessary anyway). The fix: make the damn code smaller! +- After a battle, the prices don't get reset (or, not always?) when + entering the new port. + - The "negative interest" bug is currently missing, due to using unsigned values for debt. Plus, it's cheating. It'll get added back when I either start using big numbers (floats or 64-bit ints or whatever), @@ -1,26 +1,54 @@ - .export _randi, _randl - .importzp sreg + .export _randb, _randi, _randl + .importzp sreg, tmp3 -RANDOM = 53770 ; POKEY LFSR read address, defined in the Atari OS + .include "atari.inc" -; void __fastcall__ randi(void); +; RANDOM is the POKEY LFSR read address. +; unfortunately, a read from this address will never +; return 0, since LFSR's can't do that. So there's +; extra code in here to (try to) compensate. + +; unsigned char __fastcall__ randb(void); +_randb: ; C-callable entry point + ldx #0 +randb: ; asm-callable (doesn't trash X reg) + lda RANDOM ; bit 7 of this read ends up as bit 0 of result + sta tmp3 + nop ; let the LFSR cook for a bit... + nop + lda RTCLOK ; different amount of cooking depending on whether + and #$01 ; we're on an even or odd numbered TV frame + bne @1 + nop + nop + nop +@1: + rol tmp3 ; tmp3 bit 7 now in carry + lda RANDOM + rol ; carry now in bit 0 of A + nop + nop + rts + +; unsigned int __fastcall__ randi(void); ; NB cc65's rand() returns a positive signed int, meaning ; 0 to 0x7fff. _randi: - lda RANDOM + jsr randb and #$7f tax - lda RANDOM + jsr randb rts -; void __fastcall__ randl(void); +; unsigned long __fastcall__ randl(void); _randl: - lda RANDOM + jsr randb sta sreg - lda RANDOM + jsr randb sta sreg+1 - lda RANDOM - ldx RANDOM + jsr randb + tax + jsr randb rts @@ -11,7 +11,7 @@ /* define this to use cc65's rand() instead of POKEY's RANDOM register. Leave disabled for now as POKEY never returns 0 (it's an LFSR, I should have known that would happen...) */ -// #define POKEY_RANDOM +#define POKEY_RANDOM /* define this for testing sea_battle(). it causes a pirate attack every time you leave port. Don't leave defined for @@ -73,11 +73,11 @@ extern void __fastcall__ jsleep(unsigned int j); /* Atari-specific random number functions from rand.s. Non-Atari platforms can probably just: #define initrand() _randomize() -#define randi() rand() +#define randi() ((unsigned int)rand()) #define randl() (unsigned long)((randi() << 16) | randi()) */ -#if POKEY_RANDOM +#ifdef POKEY_RANDOM #define initrand() /* no-op on Atari */ /* random positive int, 0 to 32767 */ extern unsigned int __fastcall__ randi(void); |