v1.0b: Fix a number of bugs

There are a number of bugfixes (and one subtle new feature) in v1.0b:
- Spaceship parts are no longer lost if Keen dies in the level they were
  originally found in. This required a slightly more complicated patch,
  as multiple spaceship parts could be found in the same level.
- Yorp statue messages about level locations are no-longer backwards.
- The RNDKEEN1.BAT file now uses MS-DOS line endings, so will work on
  real MS-DOS machines. (DOSBox handled the UNIX newlines fine.)
- The in-game random number generator is now seeded with a value derived
  from the randomiser seed. (This means that enemy behaviour, et al, is
  technically deterministic with the same seed now, but probably won't
  cause any player-visible changes.)

README.TXT

@@ -3,7 +3,7 @@ Commander Keen 1 Randomiser
 ===========================
 
 Author: David Gow <[email protected]>
-Version: 1.0a
+Version: 1.0b
 Website: https://davidgow.net/keen/randomiser.html
 
 

RNDKEEN1.BAT

@@ -1,5 +1,5 @@
-@ECHO OFF
-COPY LEVEL81.CK1 RNDLV81.CK1
-COPY LEVEL90.CK1 RNDLV90.CK1
-RANDKEEN %1 %2 %3 %4 %5 %6 %7 %8 %9
-CK1PATCH RNDKEEN1.PAT
+@ECHO OFF
+COPY LEVEL81.CK1 RNDLV81.CK1
+COPY LEVEL90.CK1 RNDLV90.CK1
+RANDKEEN %1 %2 %3 %4 %5 %6 %7 %8 %9
+CK1PATCH RNDKEEN1.PAT

randkeen.c

@@ -557,6 +557,36 @@ void WriteMapHintToPatch(FILE *f, int oldMap, int newMap)
 		fprintf(f, "Level %d\nrests where\nlevel %d once\nwas...\n\n", newMap, oldMap);
 }
 
+void WritePerItemPatch(FILE *f, int level, int item)
+{
+	static int curPatchItem = 0;
+	uint16_t offset = 0x4F68 + 11 * curPatchItem;
+	if (item != K1_T_JOYSTICK &&
+		item != K1_T_BATTERY &&
+		item != K1_T_VACUUM &&
+		item != K1_T_EVERCLEAR)
+		return;
+	// Make sure we don't remove the spaceship parts from the
+	// wrong levels.
+	// cmp ax, (level)
+	fprintf(f, "%%patch $%04X\t$3D $%04XW\n", offset, level);
+	// jnz +6
+	fprintf(f, "\t\t$75 $06\n");
+	// mov (GameState.got_item), 0
+	if (item == K1_T_JOYSTICK)
+		fprintf(f, "\t\t$C7 $06 $AA94W $0000W\n", level);
+	else if (item == K1_T_BATTERY)
+		fprintf(f, "\t\t$C7 $06 $AA9CW $0000W\n", level);
+	else if (item == K1_T_VACUUM)
+		fprintf(f, "\t\t$C7 $06 $AA94W $0000W\n", level);
+	else if (item == K1_T_EVERCLEAR)
+		fprintf(f, "\t\t$C7 $06 $AA94W $0000W\n", level);
+
+	uint8_t end_off = 0x4FA0 - (offset + 13);
+	fprintf(f, "\t\t$EB $%02x\n\n", end_off);
+	curPatchItem++;
+}
+
 void WritePatchHeader(FILE *f)
 {
 	fprintf(f, "%%ext ck1\n");
@@ -571,6 +601,15 @@ void WritePatchHeader(FILE *f)
 	fprintf(f, "%%patch $0FA7\t$B8 $%04XW\n", (opt_seed >> 16) & 0xFFFF);
 	fprintf(f, "\t\t$BA $%04XW\n", opt_seed & 0xFFFF);
 	fprintf(f, "\t\t$90 $90 $90 $90 $90 $90\n\n");
+
+	// Base the game's random number seed off ours.
+	uint8_t randomIndexByte = ((opt_seed >> 24) ^ (opt_seed >> 16) ^ (opt_seed >> 8) ^ opt_seed) & 0xFF;
+	// push ax
+	// mov ax, $00<seed>
+	// mov [randomIndex], ax
+	// pop ax
+	// ret
+	fprintf(f, "%%patch $C0AC $50 $B8 $%02X $00 $A1 $57 $51 $58 $C3\n\n");
 
 	if (opt_startPogo)
 		fprintf(f, "%%patch $900E $01\n\n");
@@ -587,7 +626,7 @@ void WritePatchFooter(FILE *f)
 void PrintBanner()
 {
 	printf("Keen 1 Randomiser\n");
-	printf("\tv1.00a\n");
+	printf("\tv1.00b\n");
 	printf("\tBy David Gow <[email protected]>\n\n");
 }
 
@@ -695,15 +734,18 @@ int main(int argc, char **argv)
 			K1_ShuffleEnemies(&vm);
 		while (slotsPerLevel[level-1]--)
 		{
+			int item = itemsPerSlot[curItemSlot];
 			// If we have the pogo at the start, or we have extra pogosticks,
 			// don't generate hints for pogo stick locations.
-			if (!(opt_startPogo || opt_extraPogo) || (itemsPerSlot[curItemSlot] != K1_T_POGOSTICK))
+			if (!(opt_startPogo || opt_extraPogo) || (item != K1_T_POGOSTICK))
 			{
-				WriteTileHintToPatch(patchFile, itemsPerSlot[curItemSlot], level);
-				if (itemsPerSlot[curItemSlot] != K1_T_GREYSKY)
-					WriteMapHintToPatch(patchFile, level, mapLocations[level-1]);
+				WriteTileHintToPatch(patchFile, item, level);
+				if (item != K1_T_GREYSKY)
+					WriteMapHintToPatch(patchFile, mapLocations[level-1], level);
 			}
-			K1_SetSpecialItem(&vm, itemsPerSlot[curItemSlot++], slotsPerLevel[level-1]);
+			K1_SetSpecialItem(&vm, item, slotsPerLevel[level-1]);
+			WritePerItemPatch(patchFile, level, item);
+			curItemSlot++;
 		}
 		sprintf(fname, "RNDLV%02d.CK1", level);
 		f = fopen(fname, "wb");