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/* source: dalan.c */
/* Copyright Gerhard Rieger 2001-2008 */
/* Published under the GNU General Public License V.2, see file COPYING */
/* idea of a low level data description language. currently only a most
primitive subset exists. */
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include "dalan.h"
/* test structure to find maximal alignment */
static struct {
char a;
long double b;
} maxalign;
/* test structure to find minimal alignment */
static struct {
char a;
char b;
} minalign;
/* test union to find kind of byte ordering */
static union {
char a[2];
short b;
} byteorder = { "01" };
struct dalan_opts_s dalan_opts = {
sizeof(int),
sizeof(short),
sizeof(long),
sizeof(char),
sizeof(float),
sizeof(double)
} ;
/* fill the dalan_opts structure with machine dependent defaults values. */
static void _dalan_dflts(struct dalan_opts_s *dlo) {
dlo->c_int = sizeof(int);
dlo->c_short = sizeof(short);
dlo->c_long = sizeof(long);
dlo->c_char = sizeof(char);
dlo->c_float = sizeof(float);
dlo->c_double = sizeof(double);
dlo->maxalign = (char *)&maxalign.b-&maxalign.a;
dlo->minalign = &minalign.b-&minalign.a;
dlo->byteorder = (byteorder.b!=7711);
}
/* allocate a new dalan_opts structure, fills it with machine dependent
defaults values, and returns the pointer. */
struct dalan_opts_s *dalan_props(void) {
struct dalan_opts_s *dlo;
dlo = malloc(sizeof(struct dalan_opts_s));
if (dlo == NULL) {
return NULL;
}
_dalan_dflts(dlo);
return dlo;
}
void dalan_init(void) {
_dalan_dflts(&dalan_opts);
}
/* read data description from line, write result to data; do not write
so much data that *p exceeds n !
return 0 on success,
-1 if the data was cut due to n limit,
1 if a syntax error occurred
*p is a global data counter; especially it must be used when calculating
alignment. On successful return from the function *p must be actual!
*/
int dalan(const char *line, char *data, size_t *p, size_t n) {
int align, mask, i, x;
size_t p1 = *p;
char c;
/*fputs(line, stderr); fputc('\n', stderr);*/
while (c = *line++) {
switch (c) {
case ' ':
case '\t':
case '\r':
case '\n':
break;
case ',':
align = 2;
while (*line == ',') {
align <<= 1;
++line;
}
mask = align - 1; /* create the bitmask */
i = (align - (p1 & mask)) & mask;
while (i && p1<n) data[p1++] = 0, --i;
if (i) { *p = p1; return -1; }
break;
case ';':
align = dalan_opts.c_int;
mask = align - 1;
i = (align - (p1 & mask)) & mask;
while (i && p1<n) data[p1++] = 0, --i;
if (i) { *p = p1; return -1; }
break;
case '"':
while (1) {
switch (c = *line++) {
case '\0': fputs("unterminated string\n", stderr);
return 1;
case '"':
break;
case '\\':
if (!(c = *line++)) {
fputs("continuation line not implemented\n", stderr);
return 1;
}
switch (c) {
case 'n': c = '\n'; break;
case 'r': c = '\r'; break;
case 't': c = '\t'; break;
case 'f': c = '\f'; break;
case 'b': c = '\b'; break;
case 'a': c = '\a'; break;
#if 0
case 'e': c = '\e'; break;
#else
case 'e': c = '\033'; break;
#endif
case '0': c = '\0'; break;
}
/* PASSTHROUGH */
default:
if (p1 >= n) { *p = p1; return -1; }
data[p1++] = c;
continue;
}
if (c == '"')
break;
}
break;
case '\'':
switch (c = *line++) {
case '\0': fputs("unterminated character\n", stderr);
return 1;
case '\'': fputs("error in character\n", stderr);
return 1;
case '\\':
if (!(c = *line++)) {
fputs("continuation line not implemented\n", stderr);
return 1;
}
switch (c) {
case 'n': c = '\n'; break;
case 'r': c = '\r'; break;
case 't': c = '\t'; break;
case 'f': c = '\f'; break;
case 'b': c = '\b'; break;
case 'a': c = '\a'; break;
#if 0
case 'e': c = '\e'; break;
#else
case 'e': c = '\033'; break;
#endif
}
/* PASSTHROUGH */
default:
if (p1 >= n) { *p = p1; return -1; }
data[p1++] = c;
break;
}
if (*line != '\'') {
fputs("error in character termination\n", stderr);
*p = p1; return 1;
}
++line;
break;
#if LATER
case '0':
c = *line++;
if (c == 'x') {
/* hexadecimal */ ;
} else if (isdigit(c&0xff)) {
/* octal */
} else {
/* it was only 0 */
}
break;
#endif /* LATER */
case 'x':
/* expecting hex data, must be an even number of digits!! */
while (true) {
c = *line;
if (isdigit(c&0xff)) {
x = (c-'0') << 4;
} else if (isxdigit(c&0xff)) {
x = ((c&0x07) + 9) << 4;
} else
break;
++line;
c = *line;
if (isdigit(c&0xff)) {
x |= (c-'0');
} else if (isxdigit(c&0xff)) {
x |= (c&0x07) + 9;
} else {
fputs("odd number of hexadecimal digits\n", stderr);
*p = p1; return 1;
}
++line;
if (p1 >= n) { *p = p1; return -1; }
data[p1++] = x;
}
break;
case 'A': case 'a':
case 'C': case 'c':
default: fprintf(stderr, "syntax error in \"%s\"\n", line-1);
return 1;
}
}
*p = p1; return 0;
}
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