Added first bunch of docs

AICA/SRCS/sound/Makefile

@@ -0,0 +1,43 @@
+
+ARMCC = arm-elf-gcc
+ARMAS = arm-elf-as -marm7
+ARMLD = arm-elf-ld
+
+ARMCFLAGS = -mcpu=arm7 -ffreestanding -fomit-frame-pointer -O4
+
+AS = sh-elf-as -little
+LD = sh-elf-ld -EL
+CC = sh-elf-gcc -ml
+
+
+music.srec : crt0.o dcmain.o
+	$(CC) -o $@ -Wl,--oformat,srec,-Ttext,0x8c010000 \
+		-nostartfiles crt0.o dcmain.o -lgcc
+
+dcmain.o : dcmain.c music.h
+
+crt0.o : crt0.s
+
+music.h : music.bin
+	./bintohex.pl < $< > $@
+
+music.bin : music.elf
+	arm-elf-objcopy -O binary $< $@
+
+music.elf : base.o music.o aica.o
+	$(ARMCC) $(ARMCFLAGS) -Wl,-Ttext=0 -nostartfiles -nostdlib -o $@ base.o music.o aica.o -lgcc
+
+base.o : base.s
+	$(ARMAS) -o $@ $<
+
+music.o : music.c aica.h bwv784.h
+	$(ARMCC) $(ARMCFLAGS) -c -o $@ $<
+
+aica.o : aica.c aica.h
+	$(ARMCC) $(ARMCFLAGS) -c -o $@ $<
+
+
+clean :
+	-rm -f *.o *.bin *.elf *.srec
+	-rm -f music.h
+

AICA/SRCS/sound/aica.c

@@ -0,0 +1,66 @@
+#include "aica.h"
+
+#define AICA(n) ((volatile unsigned int *)(void*)(0x800000+(n)))
+
+void aica_reset()
+{
+  int i, j;
+  volatile unsigned int *hwptr = AICA(0);
+
+  *AICA(0x2800) = 0;
+
+  /* Reset all 64 channels to a silent state */
+  for(i=0; i<64; i++) {
+    hwptr[0] = 0x8000;
+    hwptr[5] = 0x1f;
+    hwptr[1] = 0;
+    hwptr[2] = 0;
+    hwptr[3] = 0;
+    hwptr[4] = 0;
+    for(j=6; j<32; j++)
+      hwptr[j] = 0;
+    hwptr += 32;
+  }
+
+  *AICA(0x2800) = 15;
+}
+
+void play_sound(int channel, void *data, int mode, int nsamp, int freq,
+		int vol, int pan)
+{
+  volatile unsigned int *hwptr = AICA(channel<<7);
+  unsigned long freq_lo, freq_base = 5644800;
+  int freq_hi = 7;
+
+  /* Set sample format and buffer address */
+  hwptr[0] = 0x4200 | (mode<<7) | (((unsigned long)data)>>16);
+  hwptr[1] = ((unsigned long)data) & 0xffff;
+  /* Number of samples */
+  hwptr[3] = nsamp;
+  /* Need to convert frequency to floating point format
+     (freq_hi is exponent, freq_lo is mantissa).
+     Formula is  freq = 44100*2^freq_hi*(1+freq_lo/1024)  */
+  while(freq < freq_base && freq_hi > -8) {
+    freq_base >>= 1;
+    --freq_hi;
+  }
+  freq_lo = (freq<<10)/freq_base;
+  /* Write resulting values */
+  hwptr[6] = (freq_hi<<11)|(freq_lo&1023);
+  /* Set volume, pan, and some other stuff */
+  ((volatile unsigned char *)(hwptr+9))[4] = 0x24;
+  ((volatile unsigned char *)(hwptr+9))[1] = 0xf;
+  ((volatile unsigned char *)(hwptr+9))[5] = vol;
+  ((volatile unsigned char *)(hwptr+9))[0] = pan;
+  hwptr[4] = 0x1f;
+  /* Enable playback */
+  hwptr[0] |= 0xc000;
+}
+
+void stop_sound(int channel)
+{
+  volatile unsigned int *hwptr = AICA(channel<<7);
+
+  /* Disable playback */
+  hwptr[0] = (hwptr[0] & ~0x4000) | 0x8000;
+}

AICA/SRCS/sound/aica.h

@@ -0,0 +1,19 @@
+/* Sample formats */
+#define MODE_16BIT 0
+#define MODE_8BIT  1
+#define MODE_ADPCM 3
+
+/* Volume 0 is max, higher is lower */
+#define VOL_MAX    0x00
+#define VOL_MIN    0xff
+
+/* Pan is 5 bit sign-value (it seems) */
+#define PAN_LEFT   0x1f
+#define PAN_RIGHT  0x0f
+#define PAN_CENTER 0x00
+
+/* Prototypes */
+extern void aica_reset(void);
+extern void play_sound(int channel, void *data, int mode, int nsamp, int freq,
+		       int vol, int pan);
+extern void stop_sound(int channel);

AICA/SRCS/sound/base.s

@@ -0,0 +1,109 @@
+#
+# Generic startup and interrupt handler for ARM7 CPU.
+#
+# Note:	Stack is allocated at 0xf000, keep the binary short.  :-)
+#
+
+	.globl	_start, timer
+
+	.text
+
+
+	# Exception vectors
+_start:
+	b	reset
+	b	undef
+	b	softint
+	b	pref_abort
+	b	data_abort
+	b	rsrvd
+	b	irq
+
+
+	# "Fast interrupt" handler
+fiq:
+
+	# Check type of interrupt
+
+	ldr	r8,intreq
+	ldr	r9,[r8]
+	and	r9,r9,#7
+	cmp	r9,#2
+	bne	fiq_done
+
+	# Type 2 is timer interrupt.
+
+	# Increment timer variable
+
+	adr	r8,timer
+	ldr	r9,[r8]
+	add	r9,r9,#1
+	str	r9,[r8]
+
+	# Request a new timer interrupt in about
+	# one millisecond
+
+	ldr	r8,fooaddr
+	mov	r9,#256-(44100/1000)
+	str	r9,[r8,#0x10]
+	mov	r9,#0x40
+	str	r9,[r8,#0x24]
+	b	fiq_done
+
+	# Return from interrupt
+
+fiq_done:
+	ldr	r8,intclr
+	mov	r9,#1
+	str	r9,[r8]
+	str	r9,[r8]
+	str	r9,[r8]
+	str	r9,[r8]
+	subs	pc,r14,#4
+
+
+intreq:
+	.long	0x802d00
+intclr:
+	.long	0x802d04
+fooaddr:
+	.long	0x802880
+timer:
+	.long	0
+
+
+	# No-op handlers for the remaining vectors
+
+undef:
+softint:
+	movs	pc,r14
+
+pref_abort:
+irq:
+rsrvd:
+	subs	pc,r14,#4
+
+data_abort:
+	subs	pc,r14,#8
+
+
+	# Reset entry point
+
+reset:
+	# Disable IRQ and enable FIQ
+	mrs	r0,CPSR
+	orr	r0,r0,#0x80
+	bic	r0,r0,#0x40
+	msr	CPSR,r0
+	# Set stack
+	mov	sp,#0xf000
+
+	# Call main
+	bl	main
+
+	# Done.  Stay put.
+done:	b	done
+
+
+	.end
+

AICA/SRCS/sound/bintohex.pl

@@ -0,0 +1,4 @@
+#!/usr/local/bin/perl
+undef $/;$z=<>;print "static unsigned char the_code[] = {";
+for($i=0;$i<length($z);$i++){if(!(7&$i)){print "\n";}
+printf " 0x%02x,",ord(substr($z,$i,1));}print "\n};\n";