Sys.c

// MT, 2015oct26

#include <assert.h>
#include <stdbool.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdarg.h>
#include <time.h>
#include <ctype.h>
#include "Sys.h"

bool Sys_is_big_endian()
{
    assert(sizeof(unsigned int)==4);

    union
    {
        unsigned int uI;
        unsigned char uC[4];
    } u = { 0x01020304 };

    return u.uC[0]==1;
}

/** Return monotonic clock time in milliseconds.
 * 
 * - See: http://stackoverflow.com/questions/361363/how-to-measure-time-in-milliseconds-using-ansi-c 
 */
uint64_t Sys_get_posix_clock_time_ms()
{
    struct timespec ts;

    if(clock_gettime(CLOCK_MONOTONIC, &ts)==0)
    {
        return (uint64_t)(ts.tv_sec*1000+ts.tv_nsec/1000000);
    }
    else
    {
        assert(false);
        return 0;
    }
}

char* Sys_create_time_str(bool const inDate, bool const inSeconds)
{
    char* retVal = NULL;
    time_t t = time(NULL);
    struct tm const * const l = localtime(&t);
    size_t const dateLen = 11,
        timeLen = 5;
    size_t len = timeLen+1, // 23:59 and '\0'
        pos = 0;

    if(inDate)
    {
        len += dateLen; // 2016/03/20-
    }
    if(inSeconds)
    {
        len += 3; // :59
    }

    size_t const byteLen = len*(sizeof *retVal);

    retVal = malloc(byteLen);
    assert(retVal!=NULL);

    if(inDate)
    {
        snprintf(retVal+pos, byteLen-pos, "%d/%02d/%02d-", l->tm_year+1900, l->tm_mon+1, l->tm_mday);

        pos += dateLen;
    }

    snprintf(retVal+pos, byteLen-pos, "%02d:%02d", l->tm_hour, l->tm_min);
    pos += timeLen;

    if(inSeconds)
    {
        snprintf(retVal+pos, byteLen-pos, ":%02d", l->tm_sec);
    }

    return retVal;
}

/** Original source: http://stackoverflow.com/questions/7831755/what-is-the-simplest-way-of-getting-user-input-in-c
 */
char* Sys_get_stdin()
{
    size_t const granularity = 20;
    size_t len = granularity,
        i = 0;
    char* retVal = malloc(len*(sizeof *retVal));
    assert(retVal!=NULL);

    while(true)
    {
        int const c = getchar();

        // At terminating zero at end of string:
        //
        if(c=='\n')
        {
            retVal[i] = '\0';
            break;
        }

        retVal[i] = c;

        // Expand buffer, if full:
        //
        if(i==(len-1))
        {
            len = len+granularity;
            retVal = realloc(retVal, len*(sizeof *retVal));
            assert(retVal!=NULL);
        }

        ++i;
    }

    return retVal;
}

/** Original source for variable arguments: http://stackoverflow.com/questions/1056411/how-to-pass-variable-number-of-arguments-to-printf-sprintf/1056424#1056424
 */
void Sys_log_line(bool const inDate, bool const inSeconds, char const * const inStr, ...)
{
    va_list argPtr;
    char * const timePtr = Sys_create_time_str(inDate, inSeconds);

    printf("%s", timePtr);
    printf(" - ");

    assert(inStr!=NULL);

    va_start(argPtr, inStr);
    vprintf(inStr, argPtr);
    va_end(argPtr);

    printf("\n");
}