libblobpack/utils.c

/*
 * utils - misc libubox utility functions
 *
 * Copyright (C) 2012 Felix Fietkau <nbd@openwrt.org>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include "utils.h"
#include <stdarg.h>
#include <stdlib.h>
#include <stdio.h>

#define foreach_arg(_arg, _addr, _len, _first_addr, _first_len) \
	for (_addr = (_first_addr), _len = (_first_len); \
		_addr; \
		_addr = va_arg(_arg, void **), _len = _addr ? va_arg(_arg, size_t) : 0)

uint64_t pack754(long double f, unsigned bits, unsigned expbits){
    long double fnorm;
    int shift;
    long long sign, exp, significand;
    unsigned significandbits = bits - expbits - 1; // -1 for sign bit

    if (f == 0.0) return 0; // get this special case out of the way

    // check sign and begin normalization
    if (f < 0) { sign = 1; fnorm = -f; }
    else { sign = 0; fnorm = f; }

    // get the normalized form of f and track the exponent
    shift = 0;
    while(fnorm >= 2.0) { fnorm /= 2.0; shift++; }
    while(fnorm < 1.0) { fnorm *= 2.0; shift--; }
    fnorm = fnorm - 1.0;

    // calculate the binary form (non-float) of the significand data
    significand = fnorm * ((1LL<<significandbits) + 0.5f);

    // get the biased exponent
    exp = shift + ((1<<(expbits-1)) - 1); // shift + bias

    // return the final answer
    return (sign<<(bits-1)) | (exp<<(bits-expbits-1)) | significand;
}

long double unpack754(uint64_t i, unsigned bits, unsigned expbits){
    long double result;
    long long shift;
    unsigned bias;
    unsigned significandbits = bits - expbits - 1; // -1 for sign bit

    if (i == 0) return 0.0;

    // pull the significand
    result = (i&((1LL<<significandbits)-1)); // mask
    result /= (1LL<<significandbits); // convert back to float
    result += 1.0f; // add the one back on

    // deal with the exponent
    bias = (1<<(expbits-1)) - 1;
    shift = ((i>>significandbits)&((1LL<<expbits)-1)) - bias;
    while(shift > 0) { result *= 2.0; shift--; }
    while(shift < 0) { result /= 2.0; shift++; }

    // sign it
    result *= (i>>(bits-1))&1? -1.0: 1.0;

    return result;
}

void *__calloc_a(size_t len, ...)
{
	va_list ap, ap1;
	void *ret;
	void **cur_addr;
	size_t cur_len;
	int alloc_len = 0;
	char *ptr;

	va_start(ap, len);

	va_copy(ap1, ap);
	foreach_arg(ap1, cur_addr, cur_len, &ret, len)
		alloc_len += cur_len;
	va_end(ap1);

	ptr = calloc(1, alloc_len);
	alloc_len = 0;
	foreach_arg(ap, cur_addr, cur_len, &ret, len) {
		*cur_addr = &ptr[alloc_len];
		alloc_len += cur_len;
	}
	va_end(ap);

	return ret;
}

#ifdef __APPLE__
#include <mach/mach_host.h>		/* host_get_clock_service() */
#include <mach/mach_port.h>		/* mach_port_deallocate() */
#include <mach/mach_init.h>		/* mach_host_self(), mach_task_self() */
#include <mach/clock.h>			/* clock_get_time() */

static clock_serv_t clock_realtime;
static clock_serv_t clock_monotonic;

static void __constructor clock_name_init(void)
{
	mach_port_t host_self = mach_host_self();

	host_get_clock_service(host_self, CLOCK_REALTIME, &clock_realtime);
	host_get_clock_service(host_self, CLOCK_MONOTONIC, &clock_monotonic);
}

static void __destructor clock_name_dealloc(void)
{
	mach_port_t self = mach_task_self();

	mach_port_deallocate(self, clock_realtime);
	mach_port_deallocate(self, clock_monotonic);
}

int clock_gettime(int type, struct timespec *tv)
{
	int retval = -1;
	mach_timespec_t mts;

	switch (type) {
		case CLOCK_REALTIME:
			retval = clock_get_time(clock_realtime, &mts);
			break;
		case CLOCK_MONOTONIC:
			retval = clock_get_time(clock_monotonic, &mts);
			break;
		default:
			goto out;
	}

	tv->tv_sec = mts.tv_sec;
	tv->tv_nsec = mts.tv_nsec;
out:
	return retval;
}

#endif