/*
  All code by Tom Fjellstrom except the mem_[im](ge|pu)t[wl]
  functions by Shawm Hargreaves (shawn@talula.demon.co.uk)
*/

#include <stdio.h>
#include <stdlib.h>
#include <memory.h>

typedef struct mfile {
   int len;
   int pos;
   void   *data;
} mfile;

mfile *mem_fopen(int len, void *f)
{
   mfile *new = NULL;
   if(!f) return NULL;

   new = calloc(1,sizeof(mfile));
   if(!new) return NULL;

   new->len = len;
   new->data = f;
   new->pos = 0;

   return new;
}

int mem_freopen(int len, void *d, mfile *f)
{
   if(!f || !d) return 0;

   f->len  = len;
   f->pos  = 0;
   f->data = d;

   return 1;
}

void mem_fclose(mfile *f)
{
// why wasn't this in the code ??? Added by MNI
	if (f->data) free(f->data);
	free(f);
	f=NULL;
}

int mem_fread(void *buf, int size, mfile *f)
{
   int i;
   char *t = NULL,*t2 = NULL; 
   if(!buf || !f) return 0;

   t = buf;
   t2 = f->data;

   for(i=0; i!=size; i++) {
      if(f->pos>=f->len || i>=f->len) return (size<i) ? size : i;
      t[i] = *(t2+f->pos);
      f->pos++;
   }

   return (size<i) ? size : i;
}

int mem_fwrite(void *buf, int size, mfile *f)
{
   int i;
   char *t = NULL,*t2 = NULL; 
   if(!buf || !f) return 0;

   t = buf;
   t2 = f->data;

   for(i=0; i!=size; i++) {
      if(f->pos>=f->len || i>=f->len) return (size<i) ? size : i;
      *(t2+f->pos) = t[i];
      f->pos++;
   }

   return (size<i) ? size : i;
}

char mem_getc(mfile *f)
{
   char tmp,*t=NULL;
   if(f->pos>=f->len) return EOF;
   t = f->data;
   tmp = *(t+f->pos);
   f->pos++;
   return tmp;
}

char mem_putc(char c, mfile *f)
{
   char *t;
   if(f->pos>=f->len) return EOF;

   t = f->data;
   *(t+f->pos) = c;
   f->pos++;

   return c;
}

int mem_igetw(mfile *f)
{
   int b1, b2;

   if ((b1 = mem_getc(f)) != EOF)
      if ((b2 = mem_getc(f)) != EOF)
	 return ((b2 << 8) | b1);

   return EOF;
}

long mem_igetl(mfile *f)
{
   int b1, b2, b3, b4;

   if ((b1 = mem_getc(f)) != EOF)
      if ((b2 = mem_getc(f)) != EOF)
	 if ((b3 = mem_getc(f)) != EOF)
	    if ((b4 = mem_getc(f)) != EOF)
	       return (((long)b4 << 24) | ((long)b3 << 16) |
		       ((long)b2 << 8) | (long)b1);

   return EOF;
}

int mem_mgetw(mfile *f)
{
   int b1, b2;

   if ((b1 = mem_getc(f)) != EOF)
      if ((b2 = mem_getc(f)) != EOF)
	 return ((b1 << 8) | b2);

   return EOF;
}

long mem_mgetl(mfile *f)
{
   int b1, b2, b3, b4;

   if ((b1 = mem_getc(f)) != EOF)
      if ((b2 = mem_getc(f)) != EOF)
	 if ((b3 = mem_getc(f)) != EOF)
	    if ((b4 = mem_getc(f)) != EOF)
	       return (((long)b1 << 24) | ((long)b2 << 16) |
		       ((long)b3 << 8) | (long)b4);

   return EOF;
}

int mem_iputw(int w, mfile *f)
{
   int b1, b2;

   b1 = (w & 0xFF00) >> 8;
   b2 = w & 0x00FF;

   if (mem_putc(b2,f)==b2)
      if (mem_putc(b1,f)==b1)
	 return w;

   return EOF;
}

long mem_iputl(long l, mfile *f)
{
   int b1, b2, b3, b4;

   b1 = (int)((l & 0xFF000000L) >> 24);
   b2 = (int)((l & 0x00FF0000L) >> 16);
   b3 = (int)((l & 0x0000FF00L) >> 8);
   b4 = (int)l & 0x00FF;

   if (mem_putc(b4,f)==b4)
      if (mem_putc(b3,f)==b3)
	 if (mem_putc(b2,f)==b2)
	    if (mem_putc(b1,f)==b1)
	       return l;

   return EOF;
}

int mem_mputw(int w, mfile *f)
{
   int b1, b2;

   b1 = (w & 0xFF00) >> 8;
   b2 = w & 0x00FF;

   if (mem_putc(b1,f)==b1)
      if (mem_putc(b2,f)==b2)
	 return w;

   return EOF;
}

long mem_mputl(long l, mfile *f)
{
   int b1, b2, b3, b4;

   b1 = (int)((l & 0xFF000000L) >> 24);
   b2 = (int)((l & 0x00FF0000L) >> 16);
   b3 = (int)((l & 0x0000FF00L) >> 8);
   b4 = (int)l & 0x00FF;

   if (mem_putc(b1,f)==b1)
      if (mem_putc(b2,f)==b2)
	 if (mem_putc(b3,f)==b3)
	    if (mem_putc(b4,f)==b4)
	       return l;

   return EOF;
}

int mem_fseek(mfile *f, int off, int mode)
{
   if(!f) return EOF;

   if(mode==SEEK_SET) {
      if(off>f->len) off=f->len;
      f->pos = abs(off);
   } else
   if(mode==SEEK_CUR) {
      if(f->pos+off>f->len) {
         f->pos=f->len;
         return EOF;
      } else
      if(f->pos+off<0) {
         f->pos = 0;
         return -1;
      }
      f->pos += off;
   } else
   if(mode==SEEK_END) {
      int os = -abs(off);
      f->pos = f->len+os;
   }

   return 0;
}

int mem_ftell(mfile *f)
{
   if(f) return f->pos;
   return -1;
}

int mem_feof(mfile *f)
{
   if(f->pos<f->len) return 0;
   return 1;
}

#ifdef STANDALONE

char data[255] = "Hello How Are you?";

int main()
{
   char t[255],tmp;
   int j;
   mfile *f = NULL;
   f = mem_fopen(data,18);
   if(!f) { printf("couldn't open mfile\n"); return 0; }

   while(!mem_feof(f)) {
      printf("%c\n",mem_getc(f));
   }

   mem_fclose(f);

   return 0;
}
#endif /* #ifdef STANDALONE */