gfile_fs_strings.c

/*
 * This file is subject to the terms of the GFX License. If a copy of
 * the license was not distributed with this file, you can obtain one at:
 *
 *              http://ugfx.io/license.html
 */
 
/********************************************************
 * The virtual string file
 ********************************************************/
 
#include "../../gfx.h"
 
#if GFX_USE_GFILE && GFILE_NEED_STRINGS
 
#include "gfile_fs.h"
 
#include <string.h>
 
// Special String VMT
static int StringRead(GFILE *f, void *buf, int size) {
    int     res;
    char    *p;
 
    if (!f->obj)
        return 0;
    
    p = ((char *)f->obj) + f->pos;
    for(res = 0; res < size && *p; res++, p++, buf = ((char *)buf)+1)
        ((char *)buf)[0] = *p;
    return res;
}
static int StringWrite(GFILE *f, const void *buf, int size) {
    if (!f->obj)
        return 0;
    
    if ((f->flags & GFILEFLG_APPEND)) {
        while(((char *)f->obj)[f->pos])
            f->pos++;
    }
    memcpy(((char *)f->obj)+f->pos, buf, size);
    ((char *)f->obj)[f->pos+size] = 0;
    return size;
}
 
static const GFILEVMT StringVMT = {
    0,                              // flags
    '_',                            // prefix
    0, 0, 0, 0,
    0, 0, StringRead, StringWrite,
    0, 0, 0,
    0, 0, 0,
    #if GFILE_NEED_FILELISTS
        0, 0, 0,
    #endif
};
 
static void gfileOpenStringFromStaticGFILE(GFILE *f, char *str) {
    if ((f->flags & GFILEFLG_TRUNC) && str)
        str[0] = 0;
    f->vmt = &StringVMT;
    f->obj = str;
    f->pos = 0;
    f->flags |= GFILEFLG_OPEN|GFILEFLG_CANSEEK;
}
 
GFILE *gfileOpenString(char *str, const char *mode) {
    GFILE   *f;
 
    // Get an empty file and set the flags
    if (!str || !(f = _gfileFindSlot(mode)))
        return 0;
 
    // File is open - fill in all the details
    gfileOpenStringFromStaticGFILE(f, str);
    return f;
}
 
#if GFILE_NEED_PRINTG
    int snprintg(char *buf, int maxlen, const char *fmt, ...) {
        int     res;
        GFILE   f;
        va_list ap;
 
        if (maxlen <= 1) {
            if (maxlen == 1) {
                *buf = 0;
                return 0;
            }
            maxlen += 1;
        }
 
        f.flags = GFILEFLG_WRITE|GFILEFLG_TRUNC;
        gfileOpenStringFromStaticGFILE(&f, buf);
 
        va_start(ap, fmt);
        res = vfnprintg(&f, maxlen-1, fmt, ap);
        va_end(ap);
        return res;
    }
    int vsnprintg(char *buf, int maxlen, const char *fmt, va_list arg) {
        GFILE   f;
 
        if (maxlen <= 1) {
            if (maxlen == 1) {
                *buf = 0;
                return 0;
            }
            maxlen += 1;
        }
 
        f.flags = GFILEFLG_WRITE|GFILEFLG_TRUNC;
        gfileOpenStringFromStaticGFILE(&f, buf);
 
        return vfnprintg(&f, maxlen-1, fmt, arg);
    }
#endif
 
#if GFILE_NEED_SCANG
    int sscang(const char *buf, const char *fmt, ...) {
        int     res;
        GFILE   f;
        va_list ap;
 
        f.flags = GFILEFLG_READ;
        gfileOpenStringFromStaticGFILE(&f, (char *)buf);
 
        va_start(ap, fmt);
        res = vfscang(&f, fmt, ap);
        va_end(ap);
        return res;
    }
 
    int vsscang(const char *buf, const char *fmt, va_list arg) {
        GFILE   f;
 
        f.flags = GFILEFLG_READ;
        gfileOpenStringFromStaticGFILE(&f, (char *)buf);
 
        return vfscang(&f, fmt, arg);
    }
#endif
 
#endif //GFX_USE_GFILE && GFILE_NEED_STRINGS