#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
char buffa[BUFSIZ];
void die(char *why) {
fprintf(stderr, "%s\n", why);
exit(1);
}
void printbinary(unsigned int num, char zero, char one, int end) {
if (num < 1) {
putchar(zero);
} else {
while (num > 0) {
unsigned int u = num & 1;
putchar(u ? one : zero);
num = num >> 1;
}
}
if (end) putchar(' ');
}
char readbinary(char *s, char zero, char one) {
int i, len = strlen(s);
char c = 0, mask = 1;
for (i = 0; i < len; i++) {
if (s[i] == one) {
c |= mask;
} else if (s[i] == zero) {
// Do nothing
} else {
die("SYNTAX ERROR");
}
mask = mask << 1;
}
return c;
}
void encode(FILE *in) {
char *fmt = "%s";
unsigned int i, j, len, cfloor;
asprintf(&fmt, "%%%ds", BUFSIZ);
for (j = 0; j < 0xffff; j++) {
if (feof(in)) {
puts("tomot");
break;
}
fscanf(in, fmt, buffa);
if ((len = strlen(buffa))) {
cfloor = 0xffff;
for (i = 0; i < len; i++)
if (buffa[i] < cfloor)
cfloor = buffa[i];
for (i = 0; i < len; i++)
printbinary(buffa[i] - cfloor, 'U', 'u', i < len - 1);
printbinary(cfloor, '?', '!', 1);
}
fscanf(in, " ");
}
free(fmt);
}
void decode(FILE *in) {
unsigned int i, j, cfloor, wdlen;
char *ufmt = " %[uU]",
*pfmt = "%[?!]",
*tfmt = " %[tom]",
wdbuf[BUFSIZ];
asprintf(&ufmt, " %%%d[uU]", BUFSIZ);
asprintf(&pfmt, "%%%d[?!] ", BUFSIZ);
asprintf(&tfmt, " %%%d[tom]", BUFSIZ);
wdlen = 0;
wdbuf[0] = '\0'; // strlen(wdbuf) == 0
for (j = 0; j < 0xffff; j++) {
if (fscanf(in, pfmt, buffa) > 0) {
// Finish reading a word
if (wdlen < 1) die("SYNTAX ERROR");
wdbuf[wdlen] = '\0';
cfloor = readbinary(buffa, '?', '!');
for (i = 0; i < wdlen; i++)
wdbuf[i] += cfloor;
// Don't print immediately
wdlen = 0;
} else if (fscanf(in, ufmt, buffa) > 0) {
if (wdlen == 0 && strlen(wdbuf) > 0)
// Print previous word + space
printf("%s ", wdbuf);
wdbuf[wdlen++] = readbinary(buffa, 'U', 'u');
} else if (fscanf(in, tfmt, buffa) > 0) {
if (wdlen > 0) die("UNEXPECTED END OF MESSAGE");
if (strcmp(buffa, "tomot") != 0) die("SYNTAX ERROR");
// Print final word + newline
printf("%s\n", wdbuf);
break; // Clean exit
} else {
die("UNKNOWN ERROR");
}
}
free(ufmt);
free(pfmt);
free(tfmt);
return;
}
int main(int argc, char **argv) {
int i, mode = 0;
for (i = 1; i < argc; i++)
mode |= strcmp(argv[i], "--decode") | strcmp(argv[i], "-d");
if (mode != 0)
decode(stdin);
else
encode(stdin);
return 0;
}
