#include <stdio.h>

#define VERSION "0.01"
#define AUTHOR "Mishiki Sakana"
#define MYMAIL "osakana@ofo.jp"

void showUsage(char *filename){
	fprintf (stderr, "\"%s\" Ver. %s by %s <%s>\nUsage: %s FILE(.bmp)\n\t(if you omit FILE, read from STDIN.)\n\n",filename, VERSION, AUTHOR, MYMAIL, filename);
	return;
}

int checkBmpSig(FILE *fp){
	rewind(fp);
	if ( fgetc(fp) != 'B' || fgetc(fp) != 'M') {
		return (0);
	}
	return (1);
}

FILE *stdin2tmpfile(FILE *fp){

	FILE *ft;
	int c;

	if (fp!=stdin){return (fp);}
	ft = tmpfile();
	while((c = fgetc(fp)) != EOF){
			fputc(c, ft);
	}
	return (ft);
}


int main(int argc, char **argv){
	FILE *fp;
	char filename[255];

	if (argv[1]){
		if (strcmp(argv[1],"-h")==0 || strcmp(argv[1],"--help")==0){
			showUsage(argv[0]);
			exit(1);
		}
		strcpy (filename, argv[1]);
	}

	if ((fp = fopen (filename, "rb")) == NULL){
		fp = stdin;
		fp = stdin2tmpfile(fp);
		strcpy (filename, "STDIN");
	}

	if (!checkBmpSig(fp)){
		fprintf(stderr,"%s is NOT a bmp file.\n", filename);
		exit(1);
	}


	fseek(fp,0x1C,SEEK_SET);
	if (fgetc(fp) != 0x10){
		fprintf(stderr,"%s is NOT a 16-bit bmp file.\n", filename);
		exit(1);
	}

	fseek(fp,0x1E,SEEK_SET);
	if (fgetc(fp) != 0x00){
		fprintf(stderr,"biCompression is not 0x00. Not supported format.\n");
		exit(1);
	}


	unsigned long imgwidth;
	unsigned long imgheight;

	fseek(fp,0x12,SEEK_SET);
	fread (&imgwidth,4,1,fp);
	fread (&imgheight,4,1,fp);

	printf ("P3\n%d %d\n31\n\n",imgwidth,imgheight);

	//check the header length and skip it.
	fseek(fp,0x0A,SEEK_SET);
	int startat=fgetc(fp);
	fseek(fp,startat,SEEK_SET);

	unsigned short filebit;

	unsigned short rval=0;
	unsigned short gval=0;
	unsigned short bval=0;

	int realbitwidth=imgwidth*2;
	int bitwidth = (realbitwidth%4)?((realbitwidth/4+1)*4):(realbitwidth);

	int i=0;

	while (i<imgheight){
		int j=0;
		fseek(fp,(imgheight-i-1)*bitwidth+startat,SEEK_SET);
		while(j<realbitwidth){
			fread(&filebit,2,1,fp);
			j+=2;
			bval = filebit << 11;
			bval = bval >> 11;
			gval = filebit << 6;
			gval = gval >> 11;
			rval = filebit << 1;
			rval = rval >> 11;
			printf ("%d %d %d\n",rval,gval,bval);
		}
		i++;
	}

	fclose (fp);
}