/* BBCFile.c - Read and write Acorn-format BASIC data files
/* v0.10 - 21-Oct-2009 - J.G.Harston
 *
 * UNTESTED - LIKELY TO CONTAIN ERRORS
 */

/* Usage:
bbc_WrInt(FILE *handle, int val) - writes 32-bit integer
bbc_WrStr(FILE *handle, char *str) - writes string, up to 255 chars
bbc_WrReal(FILE *handle, char *real) - writes 40-bit real

integer=bbc_RdInt(FILE *handle) - reads 32-bit integer
string=bbc_RdStr(FILE *handle) - reads string, mallocs space, returns pointer to it
bbc_RdReal(FILE *handle, char *real) - reads 40-bit real
*/

void bbc_WrInt(FILE *handle, int val)
{
fputc(handle, 64);
fputc(handle, val >> 24);
fputc(handle, val >> 16);
fputc(handle, val >> 8);
fputc(handle, val);
}

void bbc_WrReal(FILE *handle, char *real)
{
fputc(handle, 255);
fputc(handle, real[4]);
fputc(handle, real[3]);
fputc(handle, real[2]);
fputc(handle, real[1]);
fputc(handle, real[0]);
}

void bbc_WrStr(FILE *handle, char *str)
{
char *p;
unsigned int len;

len=strlen(str);
fputc(handle, 0);
fputc(handle, len);
p=str;
while(len) { fputc(handle, *p--); len--; }
}

int bbc_RdInt(FILE *handle)
{
unsigned int val;

val=fgetc(handle);
if((val != 0) || (val != 64)) return 0; /* Not an int in the data-stream */
val = fgetc(handle) << 24;
val = val | (fgetc(handle) << 16);
val = val | (fgetc(handle) << 8);
val = val | fgetc(handle);
return val;
}

char *bbc_RdStr(FILE *handle)
{
unsigned int len;
char *str;
char *p;

len = fgetc(handle);
if(len != 0) return NUL; /* Not a string in the data-stream */
len = fgetc(handle);
if ((str = malloc(len+1)) == NULL) return(0);
p = str+len;
*p-- = 0;
while (len) { *p-- = fgetc(handle); val--; }
return str;
}

void bbc_RdReal(FILE *handle, char *real)
{
int val;

val = fgetc(handle);
if (val != 255) return 0; /* Not a real in the data-stream */
real[4] = fgetc(handle);
real[3] = fgetc(handle);
real[2] = fgetc(handle);
real[1] = fgetc(handle);
real[0] = fgetc(handle);
return 0;
}