fast-printf

fast-printf.c

#include <windows.h>
#include <stdio.h>
#include <ctype.h>

#ifdef _WIN32
#include <windows.h>
double
sec()
{
    LARGE_INTEGER freq, v;

    QueryPerformanceFrequency(&freq);
    QueryPerformanceCounter(&v);

    return v.QuadPart / (double)freq.QuadPart;
}

#else
#include <sys/time.h>
#include <fcntl.h>
double
sec()
{
    struct timeval tv;

    gettimeofday(&tv, NULL);

    return tv.tv_sec + tv.tv_usec / 1000000.0;
}

#endif


#define BUFSIZE 16384

typedef struct printf_output_ {
    char *buffer;               /* +0 */
    int cur;                    /* +4 */
    HANDLE fd;
    int bufsize;
} printf_output;

printf_output *
printf_open(const char *path)
{
    printf_output *ret;
    HANDLE h = CreateFile(path, GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, 0, NULL);

    if (h == INVALID_HANDLE_VALUE) {
        return NULL;
    }

    ret = malloc(sizeof(*ret));

    ret->fd = h;
    ret->cur = 0;
    ret->bufsize = BUFSIZE;
    ret->buffer = malloc(BUFSIZE);

    return ret;
}

int write_total;
printf_output *log_file;
FILE *log_file2;

static void
flush(printf_output *out)
{
    WriteFile(out->fd, out->buffer, out->cur, NULL, NULL);
    out->cur = 0;
}

void
printf_close(printf_output *out)
{
    flush(out);
    CloseHandle(out->fd);
    free(out->buffer);
    free(out);
}

static __inline void
output(int len, printf_output *out, const char *data)
{
#if 0
    /* len = ecx
     * out = edx
     * data = sp[4] */
    __asm {
        mov esi, [esp+4];       /* data */
        push edi;
        push esi;
        mov edi, [edx];         /* out->buffer */
        mov eax, [edx+4];       /* out->cur */
        add edi, eax;           /* edi = buffer + cur */
        add eax, ecx;           /* cur += len */
        /* ecx = len */
        rep movsb;
        mov [edx+4], eax;       /* out->cur = cur */
        pop esi;
        pop edi;
        ret 4;
    }
#else
    int i;
    unsigned char *dst = (unsigned char*)out->buffer + out->cur;
    //memcpy(dst, data, len);
    //isdigit(data[0]);
    for (i=0; i<len; i++) {
        dst[i] = data[i];
    }
    out->cur += len;
#endif
}

static void
reserve(printf_output *out, int len)
{
    int bufsize = out->bufsize;
    int cur = out->cur;
    int rem = bufsize - cur;
    if (len <= rem) {
        return;
    }

    flush(out);

    if (len >= bufsize) {
        bufsize = len * 2;
        free(out->buffer);
        out->buffer = malloc(bufsize);
    }
}

//int __declspec(noinline)
//fast_fprintf(printf_output *out,
//             const char *fmt,
//             ...)
//{
//    //int len = strlen(fmt);
//    int len = 17;
//
//    reserve(out, len);
//    output(out, (unsigned char*)fmt, len);
//
//    return len;
//}

static int
output_digit(printf_output *out, int v)
{
    char buffer[32];
    int cur = 31;
    int neg = 0;
    int len;

    if (v < 0) {
        neg = 1;
        v = -v;
    }

    while (v>=10) {
        int out = v%10;
        buffer[cur--] = out + '0';
        v /= 10;
    }

    buffer[cur--] = v + '0';

    if (neg) {
        buffer[cur--] = '-';
    }

    len = 31-cur;

    reserve(out, len);
    output(len, out, buffer + cur + 1);

    return len;
}

static int
output_hex(printf_output *out, unsigned int v)
{
    char buffer[32];
    int cur = 31;
    static const char tbl[] = "0123456789abcdef";

    int len;
    while (v>=16) {
        int out = v&15;
        buffer[cur--] = tbl[out];
        v >>= 4;
    }

    buffer[cur--] = tbl[v];

    len = 31-cur;

    reserve(out, len);
    output(len, out, buffer + cur + 1);

    return len;
}

int __declspec(noinline)
fast_fprintf(printf_output *out,
             const char *fmt,
             int v0, int v1, int v2)
{
    int len = 2 + 3 + 5 + 1;
    reserve(out, 2);
    output(2, out, "x=");
    len += output_digit(out, v0);
    reserve(out, 3);
    output(3, out, " y=");
    len += output_digit(out, v1);
    reserve(out, 5);
    output(5, out, " sum=");
    len += output_digit(out, v2);
    reserve(out, 1);
    output(1, out, "\n");

    return len;
}


int
sum_printf2(unsigned char *data, int w, int h)
{
    int ret = 0;
    int xi, yi;
    for (yi=0; yi<h; yi++) {
        for (xi=0; xi<w; xi++) {
            ret += data[yi*w + xi];
            //isdigit((char)ret);
            write_total += fast_fprintf(log_file, "x=%d y=%d sum=%d\n", xi, yi, ret);
            //write_total += fprintf(log_file2, "x=%d y=%d sum=%d\n", xi, yi, ret);
        }
    }
    return ret;
}

int main(int argc, char **argv)
{
    unsigned char *data;
    int w = 640, h = 480;
    int v;
    double start, end;
    int i;

    if (argc >= 3) {
        w = atoi(argv[1]);
        h = atoi(argv[2]);
    }

    log_file = printf_open("log.txt");
    log_file2 = fopen("log2.txt", "w");

    data = malloc(w*h);
    memset(data, 0, w*h);

    for (i=0; i<5; i++) {
        double dt;
        const char *name = "??";
        write_total = 0;

        start = sec();
        v = sum_printf2(data, w, h);
        name = "printf2";
        end = sec();

        dt = end-start;

        printf("%10s: %d %d %d %f[usec] %f[nsec/byte]\n", name, w, h, v, dt*1000*1000.0, dt/(write_total)*1000*1000*1000.0);
    }

    printf_close(log_file);
}