	AltOS - 8051 operating system for Altus-Metrum projects

Copyright and License

	Copyright © 2009 Keith Packard <keithp@keithp.com>

	This program is free software; you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation; either version 2 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful, but
	WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
	General Public License for more details.

	You should have received a copy of the GNU General Public License along
	with this program; if not, write to the Free Software Foundation, Inc.,
	59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.

Tasking API:

	 * Multi-tasking
	 * Non-preemptive
	 * Unix-style sleep/wakeup scheduling
	 * Strict round-robin, no priorities

	uint8_t ao_sleep(void *wchan)

		Puts current task to sleep. Will wake up when wchan is
		signalled (returning 0), or when an alarm has expired
		(returning 1).
	
	void ao_wakeup(void *wchan)

		Wakeup all tasks sleeping on wchan

	void ao_add_task(struct ao_task *task, void (*start)(void))

		Adds a task to the queue of available tasks

	void ao_start_scheduler(void)

		Invokes the scheduler, starting the operating system

	void ao_yield(void)

		Switches to another task which is ready to run. Allows
		tasks which want to run for a while to give up the CPU
		without needing to sleep

	void ao_panic(uint8_t reason)

		Any fatal error should call this function, which can
		display the error code in some cryptic fashion.

	void ao_wake_task(struct ao_task *task)

		Wake the task as if the wchan it is waiting on had
		been signalled.

	void ao_alarm(uint16_t delay)

		Queue an alarm to expire 'delay' ticks in the future.
		The alarm will cause the task to wake from ao_sleep
		and return 1. Alarms are cancelled if the task is
		awoken by ao_wakeup or ao_wake_task.

	void ao_exit(void)

		Stop the current task and remove it from the list of
		available tasks.

Timer API

	 * Regular timer ticks (at 100Hz, by default)
	 * All time values are in ticks

	 uint16_t ao_time(void)

		Returns the curent tick count

	void ao_delay(uint16_t delay)

		Suspend task execution for 'delay' ticks.

DMA API

	 * Static DMA entry allocation

	uint8_t ao_dma_alloc(uint8_t *done)

		Allocates one of the 5 DMA units on the cc1111
		processor. When this DMA unit is finished, it will
		set *done to 1 and wakeup anyone waiting on that.

	void ao_dma_set_transfer(uint8_t id, void *src, void *dst,
				 uint16_t count, uint8_t cfg0, uint8_t cfg1)

		Prepares the specified DMA unit for operation.

	void ao_dma_start(uint8_t id)

		Start DMA on the specified channel.

	void ao_dma_trigger(uint8_t id)

		Manually trigger a DMA channel

	void ao_dma_abort(uint8_t id)

		Abort a pending DMA transfer, signalling
		that by setting the associated 'done' to
		AO_DMA_ABORTED and waking any task
		sleeping on that.
