C89 Hello World Multi-Thread Rand

/*************************
    Alaestor FGL 2016
      Windows 32-bits
     ISO/IEC 9899:1990
     alaestor@null.net
*************************/

/*
    Warning and Error Free when compiled with tags ...
    -std=c89 -wall -wextra -O3 -pedantic
    -fexpensive-optimizations -fomit-frame-pointer
*/

/*
    1 thread per logical core
    each thread randomly generates strings until one makes "Hello World"
    Once successful, the randomly generated string is then printed to stdout
*/

#include <stdio.h>
#include <stdlib.h>
#include <windows.h>
#include <limits.h>


/* Uncomment DEBUG for Two-Thread, Instant-Solve test */
/* Uncomment PAUSE for the program to prompt for enter key before continuing */
/*#define DEBUG*/
/*#define PAUSE*/
#define LEN (sizeof(str)) /* 12 = 11 chars + 1 null term */

/* work return codes (unsigned int) */
#define FAILURE_LOOP_MAX 69
#define FAILURE_FINISHED 9001
#define SUCCESS 1337

/* Global Thread State */
unsigned int work_finished;

/* Global Constants */
const char chlist[] = " ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz\0";
const char str[] = "Hello World"; /* may be replaced with anything <max_len */

/* Function Prototypes */
unsigned int WINAPI work(void *buffer);
int e(char *errstr);

int main(int argc, char **argv)
{
    int i;
    int count = 0;
    int cores = 0;
    unsigned int ec = 0;
    const size_t cache = 64; /* Sys_Logical_Proc_Info ... MinGW Bug */
    const size_t max_len = cache / sizeof(char);
    char *buffers[MAXIMUM_WAIT_OBJECTS];
    HANDLE threads[MAXIMUM_WAIT_OBJECTS];
    SYSTEM_INFO sysinfo;

    (void)argc,(void)argv;
    work_finished = 0;

    if (LEN >= max_len)
    { /* sanity check */
        e(" String to be generated is over largest cache line");
        return 0;
    }

    GetSystemInfo(&sysinfo);
    cores = sysinfo.dwNumberOfProcessors;

    #ifdef DEBUG
    cores = 2;
    #endif /* DEBUG */

    for (i = 0; i < cores && i < MAXIMUM_WAIT_OBJECTS-1; i++, count++)
    {
        buffers[i] = malloc(cache);
        if (buffers[i] == NULL)
        {
            e(" Malloc returned NULL");
            goto ROUTINE_EXIT;
        }

        threads[i] = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE) work,
                                  buffers[i], 0, NULL);
        if (threads[i] == NULL)
        {
            e(" CreateThread returned NULL");
            goto ROUTINE_EXIT;
        }
    }

    puts("\n Generating Hello World String...");
    WaitForMultipleObjects(cores, threads, 0, INFINITE);
    puts(" Finished!");

    for (i = 0; i < count-1 && ec == 0; i++)
    { /* find the buffer that exited */
        GetExitCodeThread(threads[i], (PDWORD)&ec);
        if (ec != SUCCESS)
            ec = 0;
        else
            ec = i;
    }

    /* print generated string */
    printf("\n    %s\n\n",buffers[ec]);

    ROUTINE_EXIT: /* goto label: kill existing threads and buffers */
    work_finished = 1;

    Sleep(20); /* so threads may have a chance to exit */

    for (i = 0; i < count; i++)
    { /* Close thread handles and free associated buffers */
        CloseHandle(threads[i]);
        free(buffers[i]);
    }

    #ifdef PAUSE
    puts(" Press Enter To End Process");
    getchar();
    #endif /* PAUSE */

    return 0;
}

unsigned int WINAPI work(void *buffer)
{
    int i;
    char result[LEN];
    unsigned int loopcount = 0;

    do
    { /* Generate random characters in an array to match desired output */
        if (loopcount++ == UINT_MAX-1) /* Oblivion check */
            ExitThread(FAILURE_LOOP_MAX);

        if (work_finished == 1) /* another thread has finished */
            ExitThread(FAILURE_FINISHED);

        for (i = LEN-1; i >= 0; i--) /* rand characters to compose string */
            result[i] = chlist[rand() % sizeof(chlist) - 1];

        #ifdef DEBUG
        memcpy(result, str, LEN);
        #endif /* DEBUG */

        Sleep(0); /* So that the thread wont hog timeslices */
    } while (memcmp(&result[0], str, LEN));

    memcpy(buffer, (const void *)result, LEN);

    ExitThread(SUCCESS);
}

int e(char *errstr)
{
    printf("=== ERROR ===\n"
           "%s\n", errstr);

    #ifdef PAUSE
    puts(" Press Enter To Continue Application");
    getchar();
    #endif /* PAUSE */

    return -1;
}