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#ifndef utils_h
#define utils_h
// utils.h
// n.avr.utils - AVR utilities module. {{{
//
// Copyright (C) 2004 Nicolas Schodet
//
// 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.
//
// Contact :
//        Web: http://perso.efrei.fr/~schodet/
//      Email: <contact@ni.fr.eu.org>
// }}}
#include "avrconfig.h"

#include <avr/delay.h>
#include <avr/wdt.h>
#include <inttypes.h>

/** Helper macro to build register value.  Call it like this :
 * 
 * TCCR0 = regv (FOC0, WGM00, COM01, COM0, WGM01, CS02, CS01, CS00,
 *               0,     0,     0,    0,     0,    1,    1,    1);
 *
 * The macro check that the bits are given in the right order and compute the
 * register value.  If the bits are false, the compiler will generate an
 * warning about a constant being to large.
 */
#define regv(b7, b6, b5, b4, b3, b2, b1, b0, v7, v6, v5, v4, v3, v2, v1, v0) \
    ((b7) == 7 && (b6) == 6 && (b5) == 5 && (b4) == 4 \
     && (b3) == 3 && (b2) == 2 && (b1) == 1 && (b0) == 0 \
     ? (v7) << 7 | (v6) << 6 | (v5) << 5 | (v4) << 4 \
     | (v3) << 3 | (v2) << 2 | (v1) << 1 | (v0) << 0 \
     : -1024 * 1024)

/** Delay in ns.  Do not call this macro with a variable parameter.  If you
 * want a variable delay, prefer looping over a fixed delay.
 *
 * Maximum delay is about 3.3s at 20MHz.
 *
 * Should be a inline function, but GCC do not inline like I want.
 */
#define delay_ns(ns_) \
do { \
    static const uint32_t ns = (ns_); \
    static const uint32_t t = 1000000000lu / AC_FREQ; \
    static const uint32_t t8 = t * 255 * 3; \
    static const uint32_t t16 = t * 65535 * 4; \
    if (ns <= t) \
      { \
	/* Delay shorter than 1 instruction. */ \
	asm volatile ("nop" : :); \
      } \
    else if (ns <= t * 2) \
      { \
	/* Delay shorter than 2 instruction. */ \
	asm volatile ("nop\n\tnop" : :); \
      } \
    else if (ns <= t * 3) \
      { \
	/* Delay shorter than 3 instruction. */ \
	asm volatile ("nop\n\tnop\n\tnop" : :); \
      } \
    else if (ns <= t8) \
      { \
	static const uint8_t b = (uint8_t) ((ns + t * 3 - 1) / (t * 3)); \
	_delay_loop_1 (b); \
      } \
    else if (ns <= t16) \
      { \
	static const uint16_t b = (uint16_t) ((ns + t * 4 - 1) / (t * 4)); \
	_delay_loop_2 (b); \
      } \
    else \
      { \
	static const uint8_t ob = (uint8_t) ((ns + t16 - 1) / t16); \
	static const uint16_t ib = (uint16_t) ((ns / ob + t * 4 - 1) \
					       / (t * 4)); \
	uint8_t i; \
	i = ob; \
	while (i--) \
	    _delay_loop_2 (ib); \
      } \
} while (0)

/** Shortcut for delay_ns (us * 1000). */
#define delay_us(us) delay_ns ((us) * 1000)

/** Shortcut for delay_ns (ms * 1000 * 1000). */
#define delay_ms(ms) delay_ns ((ms) * 1000 * 1000)

/** Delay in seconds.  Maximum of 256 seconds. */
extern inline void
delay_s (uint8_t s)
{
    while (s--)
	delay_ns (1000000000);
}

extern inline void
reset (void) __attribute__ ((noreturn));

/** Reset the avr using the watchdog. */
extern inline void
reset (void)
{
    wdt_enable (WDTO_15MS);
    while (1)
	;
}

#endif // utils_h