#include <math.h>
#include <string.h>
#include <strings.h>
#include <stdlib.h>
#include "buf.h"

#define TWO28 268435456.0
#define MAXINT 2147483647

/* static char *null="\0"; */

int buf_get_int(buf_type *buf)
{ char *b;
  int *res;

  b=buf->buf;
  if (b==NULL) return(0);
  if (b[0]!=1 || buf->size<5) {buf->buf=NULL; return(0); }
  b++;
  res=(int *)b;
  b+=4;
  buf->size-=5;
  buf->buf=b;
  return(*res);
}

char *buf_get_str(buf_type *buf)
{ char *b;
  int l;

  b=buf->buf;
  if (b==NULL) return("");
  if (b[0]==1 || b[0]==2) return("");
  l=strlen(b);
  if (buf->size<=l) {buf->buf=NULL; return(""); }
  buf->buf+=l+1;
  buf->size-=l+1;
  return(b);
}

float buf_get_float(buf_type *buf)
{ char *b;
  float res;
  int *mant, iexp;

  b=buf->buf;
  if (b==NULL) return(0.0);
  if (b[0]!=2 || buf->size<6) { buf->buf=NULL; return(0.0); }
  iexp=b[1];
  b+=2;
  mant=(int *)b;
  b+=4;
  buf->size-=6;
  res=(float)ldexp(*mant/TWO28, iexp);
  buf->buf=b;
  return res;
}

int buf_size(buf_type *buf)
{
  if (buf->buf==NULL) return(-1);
  return (buf->size);
}

void buf_put_int(buf_type *buf, int val)
{ char *b;

  b=buf->buf;
  if (b==NULL) return;
  b[0]=1;
  b++;
  if (buf->size<=4) {buf->buf=NULL; return; }
  *(int *)b=val;
  b+=4;
  buf->size-=5;
  buf->buf=b;
  return;
}

void buf_put_str(buf_type *buf, const char *str)
{ char *b;
  int l;

  if (str[0]<=2 && str[0]!='\0') { buf->buf=NULL; return; };
  b=buf->buf;
  if (b==NULL) return;
  l=strlen(str);
  if (buf->size<=l) { buf->buf=NULL; return; }
  strcpy(b, str);
  buf->buf+=l+1;
  buf->size-=l+1;
}

int buf_nint(float val)
{ int res;

  if (val<0) {
    if (val<-MAXINT) {
      return(-MAXINT);
    } else {
      return(val-0.5);
    }
  } else {
    if (val>MAXINT) {
      return(MAXINT);
    } else {
      return(val+0.5);
    }
  }
}
  
void buf_put_float(buf_type *buf, float val)
{ char *b;
  double d;
  int iexp;
  int mant;

  b=buf->buf;
  if (b==NULL) return;
  if (buf->size<=4) {buf->buf=NULL; return; }
  d=frexp((double)val, &iexp);
  mant=buf_nint(d*TWO28);
  if (iexp>127) iexp=127;
  if (iexp<-128) iexp=-128;
  b[0]=2;
  b[1]=iexp;
  b+=2;
  *(int *)b=mant;
  b+=4;
  buf->size-=6;
  buf->buf=b;
}

void buf_put_end(buf_type *buf)
{ buf->buf=buf->start;
  buf->usize=buf->isize-buf->size;
  buf->size=buf->usize;
}

void buf_put_start(buf_type *buf)
{ buf->buf=buf->start;
  buf->size=buf->isize;
}

void buf_reset(buf_type *buf)
{ buf->buf=buf->start;
  buf->size=buf->usize;
}

buf_type *buf_create(size_t size)
{ buf_type *buf;

  buf=malloc(sizeof(*buf));
  buf->start=malloc(size);
  buf->isize=size;
  return(buf);
}

void buf_free(buf_type *buf)
{ free(buf->buf);
  free(buf);
}