machdep.c

/*
//	machdep.c
//
//	Machine dependencies checker
//
//	(C) R.P.Bellis 1993
*/

#include <stdlib.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <time.h>

void byte_order(FILE *f)
{
	union {
		struct {
			uint8_t	field1;
			uint8_t	field2;
		} bytes;
		uint16_t	value;
	} tmp;

	tmp.value = 0;
	tmp.bytes.field1 = 1;

	if (tmp.value == 0x0001) {
		fprintf(f, "#define MACH_BYTE_ORDER_LSB_FIRST\n");
	} else if (tmp.value == 0x0100) {
		fprintf(f, "#define MACH_BYTE_ORDER_MSB_FIRST\n");
	} else {
		fprintf(stderr, "cannot determine byte order\n");
		exit(EXIT_FAILURE);
	}
}

void bitfield_order(FILE *f)
{
	union {
		struct {
			unsigned int	field1 : 1;
			unsigned int	dummys : 6;
			unsigned int	field2 : 1;
		} bits;
		unsigned int		value;
	} tmp;

	tmp.value = 0;
	tmp.bits.field1 = 1;

	if (tmp.value == 1) {
		fprintf(f, "#define MACH_BITFIELDS_LSB_FIRST\n");
	} else {
		fprintf(f, "#define MACH_BITFIELDS_MSB_FIRST\n");
	}
}

int main(int argc, char *argv[])
{
	FILE		*f;
	char		*path;
	time_t		tp;

	if (argc != 2) {
		fprintf(stderr, "usage: machdep <outfile>\n");
		return EXIT_FAILURE;
	}
	path = argv[1];

	/* Open output stream */
	if ((f = fopen(path, "w")) == NULL) {
		perror("fopen");
		return EXIT_FAILURE;
	}

	/* Add head of output file */
	tp = time(NULL);
	fprintf(f, "/*\n");
	fprintf(f, " *\tmachdep.h generated by machdep at %s", ctime(&tp));
	fprintf(f, " */\n\n");
	fprintf(f, "#pragma once\n\n");
	fprintf(f, "#define USIM_MACHDEP_H\n");

	/* Call the determination functions */
	byte_order(f);
	bitfield_order(f);

	/* and clean up */
	fclose(f);

	return EXIT_SUCCESS;
}