# HG changeset patch
# User John Tsiombikas <nuclear@member.fsf.org>
# Date 1519385377 -7200
# Node ID 995d42b339747b6a49018f9c595524ba9fecc95c
# Parent  555b986cc4208b1e47eeeef4de5cf13a77ba52bb
serial output

diff -r 555b986cc420 -r 995d42b33974 README
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/README	Fri Feb 23 13:29:37 2018 +0200
@@ -0,0 +1,27 @@
+Amiga floppy boot test
+----------------------
+Bootblock code in src/boot/boot.s uses the Amiga exec in ROM to load the
+flat binary image from from the first N sectors to address 0x10000, and jumps
+there. The size of the binary is patched immediately before the first
+instruction of the boot code by tools/mk_adf.py.
+
+Linkscript puts code from the .startup segment (src/startup.s) at the load
+address, and it starts by setting the trap0 exception vector to point to the
+next instruction and executes a trap 0, to enter supervisor mode and take
+complete control of the system. Then it clears .bss, sets the stack and calls
+the C main function.
+
+A few words about the graphics hack
+-----------------------------------
+The IFS fractal is calculated in 16.16 fixed point, using a mersenne twister
+random number generator (src/rng.c) for picking an IFS transformation to do each
+time. Two bitplanes are enabled both pointing to the same IFS pixel buffer, with
+a few scanlines offset and a different per-pixel scroll (data fetch delay) in
+BPLCON1. The palette is set up in a way to give priority to bitplane 0, i.e. use
+green for pixels with bit 0 set, and use a shadow color for pixels which have
+only bit 1 set. This gives the illusion of a shadow layer.
+
+Serial debug output
+-------------------
+Serial comm needs RTS/CTS (hardware) flow control.
+  stty 38400 crtscts cs8 -parenb -ixon -ixoff raw -iutf8 -F /dev/ttyUSB0
diff -r 555b986cc420 -r 995d42b33974 src/hwregs.h
--- a/src/hwregs.h	Thu Feb 22 14:46:32 2018 +0200
+++ b/src/hwregs.h	Fri Feb 23 13:29:37 2018 +0200
@@ -345,6 +345,10 @@
 #define REG_COPJMP1		REG(REGN_COPJMP1)
 #define REG_COPJMP2		REG(REGN_COPJMP2)
 
+#define REG_SERPER		REG(REGN_SERPER)
+#define REG_SERDATR		REG(REGN_SERDATR)
+#define REG_SERDAT		REG(REGN_SERDAT)
+
 /* ------ bits ------- */
 #define SETBITS(x)	((x) | 0x8000)
 #define CLRBITS(x)	(x)
@@ -425,4 +429,16 @@
 #define CIAA_PA_FIR0	0x40
 #define CIAA_PA_FIR1	0x80
 
+enum {
+	SERDATR_STOP8	= 0x0100,
+	SERDATR_STOP9	= 0x0200,
+	SERDATR_RXD		= 0x0800,
+	SERDATR_TSRE	= 0x1000,
+	SERDATR_TBE		= 0x2000,
+	SERDATR_RBF		= 0x4000,
+	SERDATR_OVRUN	= 0x8000
+};
+
+#define ADKCON_UARTBRK	0x0800
+
 #endif	/* HWREGS_H_ */
diff -r 555b986cc420 -r 995d42b33974 src/main.c
--- a/src/main.c	Thu Feb 22 14:46:32 2018 +0200
+++ b/src/main.c	Fri Feb 23 13:29:37 2018 +0200
@@ -2,9 +2,14 @@
 #include "intr.h"
 #include "copper.h"
 #include "rng.h"
+#include "serial.h"
 
-#define BPLSZ  (320 / 8 * 256)
-static unsigned char fb0[BPLSZ];
+#define SCR_W	336
+#define SCR_H	256
+#define HMOD	((SCR_W - 320) / 8)
+
+#define BPLSZ  (SCR_W / 8 * SCR_H)
+static unsigned char fb0[BPLSZ + 3 * SCR_W];
 
 extern uint16_t dbgval;
 
@@ -29,8 +34,7 @@
 		: "a0", "d0")
 
 static uint32_t coplist[] = {
-	COPPER_MOVE(REGN_BPL1PTH, 0),
-	COPPER_MOVE(REGN_BPL1PTL, 0),
+	0, 0, 0, 0,	/* placeholder of bitplane pointer setting */
 
 	COPPER_MOVE(REGN_COLOR0, 0x234),
 	COPPER_VWAIT(15),
@@ -52,22 +56,31 @@
 {
 	int32_t x = 0, y = 0;
 
+	ser_init(38400);
+	ser_print("Amiga debug console initialized\n");
+
 	REG_INTENA = SETBITS(INTEN_VERTB | INTEN_MASTER);
 
 	REG_DMACON = CLRBITS(DMA_ALL);
-	REG_BPLCON0 = BPLCON0_COUNT(1) | BPLCON0_COLOR;
-	REG_BPLCON1 = 0;
+	REG_BPLCON0 = BPLCON0_COUNT(2) | BPLCON0_COLOR;
+	REG_BPLCON1 = 0xfa;
+	REG_BPL1MOD = HMOD - 2;
+	REG_BPL2MOD = HMOD - 2;
 	REG_DIWSTART = 0x2981;
 	REG_DIWSTOP = 0x29c1;
-	REG_DDFSTART = 0x38;
+	REG_DDFSTART = 0x30;
 	REG_DDFSTOP = 0xd0;
 
 	REG_COLOR0 = 0x235;
-	REG_COLOR1 = 0x2f5;
+	REG_COLOR1 = 0x2e5;
+	REG_COLOR2 = 0x113;
+	REG_COLOR3 = 0x2e5;
 
 	wait_vblank();
-	coplist[0] = COPPER_MOVE(REGN_BPL1PTH, (uint32_t)fb0 >> 16);
-	coplist[1] = COPPER_MOVE(REGN_BPL1PTL, (uint32_t)fb0);
+	coplist[0] = COPPER_MOVE(REGN_BPL1PTH, ((uint32_t)fb0 + 3 * SCR_W / 8) >> 16);
+	coplist[1] = COPPER_MOVE(REGN_BPL1PTL, (uint32_t)fb0 + 3 * SCR_W / 8);
+	coplist[2] = COPPER_MOVE(REGN_BPL2PTH, (uint32_t)fb0 >> 16);
+	coplist[3] = COPPER_MOVE(REGN_BPL2PTL, (uint32_t)fb0);
 	REG32_COP1LC = (uint32_t)coplist;
 	REG_COPJMP1 = 0;
 
@@ -105,11 +118,15 @@
 		py = 128 - (x >> 11);
 
 		if(py >= 0) {
-			pptr = fb0 + (py * 320 + px) / 8;
+			pptr = fb0 + (py * SCR_W + px) / 8;
 			*pptr = *pptr | (0x80 >> (px & 7));
 		}
 
-		wait_vblank();
+		if((REG_CIAA_PORTA & CIAA_PA_FIR0) == 0) {
+			ser_print("restarting fractal\n");
+			wait_vblank();
+			clear_bpl(fb0);
+		}
 	}
 
 	return 0;
diff -r 555b986cc420 -r 995d42b33974 src/serial.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/serial.c	Fri Feb 23 13:29:37 2018 +0200
@@ -0,0 +1,48 @@
+#include "hwregs.h"
+#include "serial.h"
+
+#define CLK		3546895
+#define BVAL(b)	(CLK / (b) - 1)
+
+static inline uint16_t baudval(int baud)
+{
+	switch(baud) {
+	case 110: return BVAL(110);
+	case 300: return BVAL(300);
+	case 600: return BVAL(600);
+	case 1200: return BVAL(1200);
+	case 2400: return BVAL(2400);
+	case 4800: return BVAL(4800);
+	case 9600: return BVAL(9600);
+	case 14400: return BVAL(14400);
+	case 19200: return BVAL(19200);
+	case 38400: return BVAL(38400);
+	case 57600: return BVAL(57600);
+	case 115200: return BVAL(115200);
+	default:
+		break;
+	}
+	return BVAL(baud);
+}
+
+void ser_init(int baud)
+{
+	REG_SERPER = baudval(baud) & 0x7fff;
+}
+
+/*
+void ser_putchar(int c)
+{
+	REG_SERDAT = ((uint16_t)c & 0xff) | 0x100;
+}
+*/
+
+void ser_print(const char *s)
+{
+	while(*s) {
+		if(*s == '\n') {
+			ser_putchar('\r');
+		}
+		ser_putchar(*s++);
+	}
+}
diff -r 555b986cc420 -r 995d42b33974 src/serial.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/serial.h	Fri Feb 23 13:29:37 2018 +0200
@@ -0,0 +1,21 @@
+#ifndef SERIAL_H_
+#define SERIAL_H_
+
+#include "hwregs.h"
+
+/* dff030 is REG_SERDAT
+ * dff018 is REG_SERDATR
+ * bit 13 of SERDATR is TBE (transmit buffer empty)
+ */
+#define ser_putchar(c) \
+	asm volatile( \
+		"or.w #0x100, %0\n\t" \
+		"0: btst #13, 0xdff018\n\t" \
+		"beq 0b\n\t" \
+		"move.w %0, 0xdff030\n\t" \
+		:: "d"((int16_t)c))
+
+void ser_init(int baud);
+void ser_print(const char *s);
+
+#endif	/* SERIAL_H_ */