Prototype audio-only player, which uses a different strategy for

scheduling audio + video.

Use a combined "fat" audio + video opcode that combines several
features:
- constant cycle count of 73 cycles/opcode (=14364 Hz)
- page and content are controlled per opcode
- each opcode does 4 offset stores (hence 57456 stores/sec)
- tick speaker twice per opcode, with varying duty cycles 4 .. 70 in
  units of 2 cycles
  - thus 32 opcodes, or 5-bit audio @ 14364 Hz

The price for this is that we need per-page variants of the opcodes,
and at 53 bytes/opcode they won't (quite) all fit even in AUX RAM.

The good news is that with some further work it should be possible
to reduce this footprint by having opcodes share implementation by
JMPing into a common tail sequence.

Also introduce some ticks in approximately correct places during the
ACK slow path, as a proof of concept that this does mitigate the
clicking.

This works and gives reasonable quality audio!

audiotest/audiotest/Makefile

@@ -0,0 +1,251 @@
+#
+#  Makefile
+#  Apple2BuildPipelineSample
+#
+#  Part of a sample build pipeline for Apple II software development
+#
+#  Created by Quinn Dunki on 8/15/14.
+#  One Girl, One Laptop Productions
+#  http://www.quinndunki.com
+#  http://www.quinndunki.com/blondihacks
+#
+
+include make/head.mk
+
+# Customize this file to control what gets built, what machines to
+# target, where in memory to put it, etc.
+
+# The name of your system or binary file to build goes here:
+PGM=audiotest
+
+# Uncomment the one you want below (the first one is the default):
+#    MACHINE = apple2
+#    MACHINE = apple2-dos33
+#    MACHINE = apple2-system
+#    MACHINE = apple2-loader
+#    MACHINE = apple2-reboot
+    MACHINE = apple2enh
+#    MACHINE = apple2enh-dos33
+#    MACHINE = apple2enh-system
+#    MACHINE = apple2enh-loader
+#    MACHINE = apple2enh-reboot
+
+# Uncomment the appropriate project type.  If your entry point is
+# main() in a .c file, then your project type is cc65.  If your
+# entry point is in an assembly file, then you project type is
+# ca65:
+#    PROJECT_TYPE = cc65
+PROJECT_TYPE = ca65
+
+# Uncomment and set this to your starting address in Apple II memory
+# if necessary:
+    START_ADDR = 8000
+
+# Set the default CPU to assemble for.  You can change this in the
+# body of a .s file using control commands like ".PC02".  Uncomment
+# the one you want below (the first one is the default):
+#    CPU = 6502
+#    CPU = 65SC02
+    CPU = 65C02
+#    CPU = 65816
+# Note: You can assemble for 65816 in 16-bit mode but the C compiler
+# will only produce 8-bit code.
+
+# Add any other directories where you are putting C or assembly source
+# files to this list:
+SRCDIRS+=
+
+# If you have a non-standard cc65 install, you may need to change
+# some of these.  Uncomment the following line and change it to the
+# correct path to CC65_HOME if the default is not correct.  If you
+# are using cc65 v2.13.3, the default is:
+# 	/usr/local/lib/cc65
+# If you are using cc65 v2.17, the default is:
+# 	/usr/local/share/cc65
+#    export CC65_HOME := /path/to/your/cc65/directory
+#
+# If the path to the cc65 binaries is not correct, uncomment this
+# line and change it:
+#    CC65_BIN = /usr/local/bin
+
+# If you want to add arguments to the compile commandline, add them
+# to this variable:
+#    CFLAGS += -Os
+
+# If you want to add arguments to the assembly commandline, add them
+# to this variable:
+#    ASMFLAGS += -g
+
+# If you want to add arguments to the link commandline, add them to
+# this variable:
+#    LDFLAGS += -v
+    LDFLAGS += -Wl --dbgfile,audiotest.dbg
+
+# If you want to add arguments to the BASIC tokenizer commandline,
+# add them to this valiable:
+#    BASICFLAGS += --optimize
+
+# If you want to link the lores graphics driver with your executable,
+# uncomment the next line.
+#    DRIVERS += loresgr
+#
+# To use the lores driver, add code which looks like this to your
+# project:
+#
+# 	#include "drivers/a2_lores_drv.h"
+#       int main(void)
+#       {
+# 	    tgi_install(&a2_lores_drv);
+# 	    tgi_init();
+# 	    // Use the graphics driver
+# 	    tgi_uninstall();
+# 	}
+#
+# Read the $CC65_HOME/include/tgi.h file to see what the
+# driver interface provides.  Also check out
+# $CC65_HOME/include/apple2.h to see the colour definitions.
+
+# If you want to link the hires graphics driver with your executable,
+# uncomment the next line.
+#    DRIVERS += hiresgr
+#
+# To use the hires driver, add code which looks like this to your
+# project:
+#
+# 	#include "drivers/a2_hires_drv.h"
+#       int main(void)
+#       {
+# 	    tgi_install(&a2_hires_drv);
+# 	    tgi_init();
+# 	    // Use the graphics driver
+# 	    tgi_uninstall();
+# 	}
+#
+# Read the $CC65_HOME/cc65/include/tgi.h file to see what the
+# driver interface provides.  Also check out
+# $CC65_HOME/include/apple2.h to see the colour definitions.
+
+# If you want to link the extended memory driver with your executable,
+# uncomment the next line.
+#    DRIVERS += auxmem
+#
+# To use the auxmem driver, add code which looks like this to your
+# project:
+#
+# 	#include "drivers/a2_auxmem_drv.h"
+#       int main(void)
+#       {
+# 	    em_install(&a2_auxmem_drv);
+# 	    // Use the auxmem driver
+# 	    em_uninstall();
+# 	}
+#
+# Read the $CC65_HOME/include/em.h file to see what the
+# driver interface provides.
+
+# If you want to link the joystick driver with your executable,
+# uncomment the next line.
+#    DRIVERS += joystick
+#
+# To use the joystick driver, add code which looks like this to your
+# project:
+#
+# 	#include "drivers/a2_joystick_drv.h"
+#       int main(void)
+#       {
+# 	    joy_install(&a2_joystick_drv);
+# 	    // Use the joystick driver
+# 	    joy_uninstall();
+# 	}
+#
+# Read the $CC65_HOME/include/joystick.h file to see what the
+# driver interface provides.
+
+# If you want to link the mouse driver with your executable,
+# uncomment the next line.
+#    DRIVERS += mouse
+#
+# To use the mouse driver, add code which looks like this to your
+# project:
+#
+# 	#include "drivers/a2_mouse_drv.h"
+#       int main(void)
+#       {
+# 	    mouse_install(&mouse_def_callbacks, &a2_mouse_drv);
+# 	    // Use the mouse driver
+# 	    mouse_uninstall();
+# 	}
+#
+# Read the $CC65_HOME/include/mouse.h file to see what the
+# driver interface provides.
+
+# If you want to link the serial driver with your executable,
+# uncomment the next line.
+#    DRIVERS += serial
+#
+# To use the serial driver, add code which looks like this to your
+# project:
+#
+# 	#include "drivers/a2_serial_drv.h"
+#       int main(void)
+#       {
+# 	    ser_install(&a2_serial_drv);
+# 	    // Use the serial driver
+# 	    ser_uninstall();
+# 	}
+#
+# Read the $CC65_HOME/include/serial.h file to see what the
+# driver interface provides.
+
+# If you have java installed in a non-standard location, you can set
+# the path to it by uncommenting the following line:
+#    export JAVA=/usr/bin/java
+
+# If you want to copy one or more files or directories to the target disk
+# image, add the root directory to this variable.  All files will be
+# copied from the source to the target using the same path from the source.
+#
+# For example, if you set COPYDIRS to dir and in your project you have
+# the following files:
+#     dir/mySystemFile
+#     dir/newDir/anotherFile
+#
+# Then, during the copy phase, mySystemFile will be copied into the root
+# of the disk and anotherFile will be copied into a directory named
+# newDir.  The newDir directory will be created if it does not already
+# exist.
+#
+# The name of the file to copy is checked and if it ends in:
+#     .as - It assumes the file is in AppleSingle format.  The .as
+#           suffix is stripped from the name when copied to the
+# 	    disk image.
+# .<char> - If the file ends with a single character which matches
+#           a DOS 3.3 file type (A, B, T, etc) it uses that value as
+#           the file type of the file copied to the disk image.  The
+#           single character is removed from the file name.
+#  .<TLA> - If the file ends with a three letter alpha extension, it
+#           uses that TLA as the file type of the file copied to the
+#           disk image.  The TLA is removed from the file name.
+#
+# If you do not provide any type information for your filenames,
+# it will be copied as a binary.
+#
+COPYDIRS=
+
+# Add any rules you want to execute before any compiles or assembly
+# commands are called here, if any.  You can generate .c, .s or .h
+# files for example.  You can generate data files.  Whatever you
+# might need.
+#
+# All of your commands associated with a rule _must_ start with a tab
+# character.  Xcode makes it a bit tough to type a tab character by
+# default.  Press option-tab within Xcode to insert a tab character.
+gen:
+
+# For any files you generated in the gen target above, you should
+# add rules in genclean to remove those generated files when you
+# clean your build.
+genclean:
+
+# Do not change anything else below here...
+include make/tail.mk