chuniio-brokenithm/util/dprintf.c

#ifndef NDEBUG

#include <windows.h>

#include <stdarg.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>

#include "dprintf.h"

static long dbg_buf_lock_init;
static CRITICAL_SECTION dbg_buf_lock;
static char dbg_buf[16384];
static size_t dbg_buf_pos;

void dprintf(const char *fmt, ...) {
    va_list ap;

    va_start(ap, fmt);
    dprintfv(fmt, ap);
    va_end(ap);
}

void dprintfv(const char *fmt, va_list ap) {
    long init;

    /* Static constructors in C are difficult to do in a way that works under
       both GCC and MSVC, so we have to use atomic ops to ensure that the
       buffer mutex is correctly initialized instead. */

    do {
        init = InterlockedCompareExchange(&dbg_buf_lock_init, 0, 1);

        if (init == 0) {
            /* We won the init race, global variable is now set to 1, other
               threads will spin until it becomes -1. */
            InitializeCriticalSection(&dbg_buf_lock);
            dbg_buf_lock_init = -1;
            init = -1;
        }
    } while (init >= 0);

    EnterCriticalSection(&dbg_buf_lock);

    dbg_buf_pos += vsnprintf_s(dbg_buf + dbg_buf_pos, sizeof(dbg_buf) - dbg_buf_pos,
                               sizeof(dbg_buf) - dbg_buf_pos - 1, fmt, ap);

    if (dbg_buf_pos + 1 > sizeof(dbg_buf)) {
        abort();
    }

    if (strchr(dbg_buf, '\n') != NULL) {
        OutputDebugStringA(dbg_buf);
        dbg_buf_pos = 0;
        dbg_buf[0] = '\0';
    }

    LeaveCriticalSection(&dbg_buf_lock);
}

void dwprintf(const wchar_t *fmt, ...) {
    va_list ap;

    va_start(ap, fmt);
    dwprintfv(fmt, ap);
    va_end(ap);
}

void dwprintfv(const wchar_t *fmt, va_list ap) {
    wchar_t msg[512];

    _vsnwprintf_s(msg, _countof(msg), _countof(msg) - 1, fmt, ap);
    OutputDebugStringW(msg);
}

#endif