New randomize() function for nearly all platforms

git-svn-id: svn://svn.cc65.org/cc65/trunk@1487 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/vic20/Makefile

@@ -20,6 +20,7 @@ OBJS =	_scrsize.o	\
 	conio.o		\
 	cputc.o		\
 	kbhit.o		\
+        randomize.o     \
 	readjoy.o      	\
 	write.o
 

libsrc/vic20/randomize.s

@@ -0,0 +1,21 @@
+;
+; Ullrich von Bassewitz, 05.11.2002
+;
+; void randomize (void);
+; /* Initialize the random number generator */
+;
+
+    	.export	       	_randomize
+	.import		_srand
+
+	.include	"vic20.inc"
+
+_randomize:
+        lda     VIC_LINES       ; Get overflow bit
+        asl     a               ; Shift bit 7 into carry
+        lda     VIC_HLINE       ; Get bit 1-8 of rasterline 
+        rol     a               ; Use bit 0-7
+        tax                     ; Use VIC rasterline as high byte
+        lda     TIME            ; Use 60HZ clock as low byte
+        jmp     _srand          ; Initialize generator
+

libsrc/vic20/vic20.inc

@@ -8,6 +8,7 @@
 
 ST   		= $90		; IEC status byte
 
+TIME            = $A0           ; 60HZ clock
 FNAM_LEN	= $B7		; Length of filename
 SECADR		= $B9		; Secondary address
 DEVNUM		= $BA		; Device number
@@ -30,10 +31,10 @@ PALFLAG		= $2A6		; $01 = PAL, $00 = NTSC
 ; Kernal routines
 
 ; Direct entries
-CLRSCR		= $E55F		
-KBDREAD		= $E5CF		
+CLRSCR		= $E55F
+KBDREAD		= $E5CF
 NAMED_OPEN	= $F495
-NAMED_CLOSE	= $F6DA         
+NAMED_CLOSE	= $F6DA
 PLOTCHAR	= $EAAA	 	; Char in A, color in X
 
 ; ---------------------------------------------------------------------------
@@ -46,8 +47,10 @@ NMIVec		= $0318
 ; ---------------------------------------------------------------------------
 ; I/O: 6560 VIC
 
-VIC 		= $9000
-VIC_COLOR	= $900F
+VIC 		= $9000                               
+VIC_LINES       = $9003         ; Screen lines, bit 7 is bit 0 from VIC_HLINE
+VIC_HLINE       = $9004         ; Rasterline, bits 1-8
+VIC_COLOR	= $900F         ; Border and background color
 
 ; ---------------------------------------------------------------------------
 ; I/O: 6522 VIA1