Nothing is more portable across Unices as straight C.
You might find my rough draft here easier to modify and extend than one from a distribution (due to the implicit copyright if nothing else). This code was designed to be easy to read and understand without any comments.
[Don't be afraid of that big array, the actual code is very short. And at the very bottom there are "comments" which were used to visualize and construct the bitmaps. If you can understand why the space character works despite being coded as a backslash, then you understand the whole thing. The rest is just filling out the alphabet.]
#include <stdio.h>
#include <string.h>
enum {
A = 1<<0,
B = 1<<1,
C = 1<<2,
D = 1<<3,
E = 1<<4,
F = 1<<5,
G = 1<<6,
H = 1<<7,
};
char vec[] = " 0123456789"
"abcdefghijklmnopqrstuvwxyz"
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
".,:!/\\|+-*=";
unsigned char map[sizeof(vec)][8] = {
/* */ {A, B, C, D, E, F, G, H}, /* :) */
/*0*/ {B|C|D|E|F, A|F|G, A|E|G, A|D|G, A|C|G, A|B|G, B|C|D|E|F, 0},
/*1*/ {G, F|G, G, G, G, G, G, 0},
/*2*/ {B|C|D|E|F, A|G, G, C|D|E|F, B, A, A|B|C|D|E|F|G, 0},
/*3*/ {B|C|D|E|F, A|G, G, C|D|E|F, G, A|G, B|C|D|E|F, 0},
/*4*/ {A|F, A|F, A|F, B|C|D|E|F|G, F, F, F, 0},
/*5*/ {A|B|C|D|E|F|G, A, A, B|C|D|E|F, G, A|G, B|C|D|E|F, 0},
/*6*/ {B|C|D|E|F, A, A, A|B|C|D|E|F, A|G, A|G, B|C|D|E|F, 0},
/*7*/ {B|C|D|E|F|G, G, F, E, D, C, B, 0},
/*8*/ {B|C|D|E|F, A|G, A|G, B|C|D|E|F, A|G, A|G, B|C|D|E|F, 0},
/*9*/ {B|C|D|E|F, A|G, A|G, B|C|D|E|F|G, G, G, B|C|D|E|F, 0},
/*a*/ {0, 0, B|C|D|E, F, B|C|D|E|F, A|F, B|C|D|E|G, 0},
/*b*/ {B, B, B, B|C|D|E|F, B|G, B|G, A|C|D|E|F, 0},
/*c*/ {0, 0, C|D|E, B|F, A, A, B|F, C|D|E},
/*d*/ {F, F, F, B|C|D|E|F, A|F, A|F, B|C|D|E|G, 0},
/*e*/ {0, 0, B|C|D|E, A|F, A|B|C|D|E|F, A, B|C|D|E, 0},
/*f*/ {C|D|E, B, B, A|B|C|D, B, B, B, 0},
/*g*/ {0, 0, B|C|D|E|G, A|F, A|F, B|C|D|E, F, B|C|D|E},
/*h*/ {B, B, B, B|C|D|E, B|F, B|F, A|B|F, 0},
/*i*/ {0, C, 0, B|C, C, C, A|B|C|D|E, 0},
/*j*/ {0, D, 0, D, D, D, A|D, B|C},
/*k*/ {B, B|E, B|D, B|C, B|D, B|E, A|B|E|F, 0},
/*l*/ {A|B, B, B, B, B, B, A|B|C, 0},
/*m*/ {0, 0, 0, A|C|E|F, A|B|D|G, A|D|G, A|D|G, 0},
/*n*/ {0, 0, 0, B|D|E, B|C|F, B|F, B|F, 0},
/*o*/ {0, 0, B|C|D|E, A|F, A|F, A|F, B|C|D|E, 0},
/*p*/ {0, 0, A|B|C|D|E, B|F, B|F, B|C|D|E, B, A|B},
/*q*/ {0, 0, B|C|D|E|G, A|F, A|F, B|C|D|E, F, F|G},
/*r*/ {0, 0, A|B|D|E, B|C|F, B, B, A|B, 0},
/*s*/ {0, 0, B|C|D|E, A, B|C|D|E, F, A|B|C|D|E, 0},
/*t*/ {0, C, C, A|B|C|D|E, C, C, D|E, 0},
/*u*/ {0, 0, A|F, A|F, A|F, A|F, B|C|D|E|G, 0},
/*v*/ {0, 0, A|G, B|F, B|F, C|E, D, 0},
/*w*/ {0, 0, A|G, A|G, A|D|G, A|D|G, B|C|E|F, 0},
/*x*/ {0, 0, A|F, B|E, C|D, B|E, A|F, 0},
/*y*/ {0, 0, B|F, B|F, B|F, C|F, A|D|E, B|C|D},
/*z*/ {0, 0, A|B|C|D|E|F, E, D, C, B|C|D|E|F|G, 0},
/*A*/ {D, C|E, B|F, A|G, A|B|C|D|E|F|G, A|G, A|G, 0},
/*B*/ {A|B|C|D|E, A|F, A|F, A|B|C|D|E, A|F, A|F, A|B|C|D|E, 0},
/*C*/ {C|D|E, B|F, A, A, A, B|F, C|D|E, 0},
/*D*/ {A|B|C|D, A|E, A|F, A|F, A|F, A|E, A|B|C|D, 0},
/*E*/ {A|B|C|D|E|F, A, A, A|B|C|D|E, A, A, A|B|C|D|E|F, 0},
/*F*/ {A|B|C|D|E|F, A, A, A|B|C|D|E, A, A, A, 0},
/*G*/ {C|D|E, B|F, A, A, A|E|F|G, B|F|G, C|D|E|G, 0},
/*H*/ {A|G, A|G, A|G, A|B|C|D|E|F|G, A|G, A|G, A|G, 0},
/*I*/ {A|B|C|D|E, C, C, C, C, C, A|B|C|D|E, 0},
/*J*/ {A|B|C|D|E, C, C, C, C, C, A|C, B},
/*K*/ {A|F, A|E, A|D, A|B|C, A|D, A|E, A|F, 0},
/*L*/ {A, A, A, A, A, A, A|B|C|D|E|F, 0},
/*M*/ {A|B|F|G, A|C|E|G, A|D|G, A|G, A|G, A|G, A|G, 0},
/*N*/ {A|G, A|B|G, A|C|G, A|D|G, A|E|G, A|F|G, A|G, 0},
/*O*/ {C|D|E, B|F, A|G, A|G, A|G, B|F, C|D|E, 0},
/*P*/ {A|B|C|D, A|E, A|E, A|B|C|D, A, A, A, 0},
/*Q*/ {C|D|E, B|F, A|G, A|G, A|C|G, B|D|F, C|D|E, F|G},
/*R*/ {A|B|C|D, A|E, A|E, A|B|C|D, A|E, A|F, A|F, 0},
/*S*/ {C|D|E, B|F, C, D, E, B|F, C|D|E, 0},
/*T*/ {A|B|C|D|E|F|G, D, D, D, D, D, D, 0},
/*U*/ {A|G, A|G, A|G, A|G, A|G, B|F, C|D|E, 0},
/*V*/ {A|G, A|G, B|F, B|F, C|E, C|E, D, 0},
/*W*/ {A|G, A|G, A|G, A|G, A|D|G, A|C|E|G, B|F, 0},
/*X*/ {A|G, A|G, B|F, C|D|E, B|F, A|G, A|G, 0},
/*Y*/ {A|G, A|G, B|F, C|E, D, D, D, 0},
/*Z*/ {A|B|C|D|E|F|G, F, E, D, C, B, A|B|C|D|E|F|G, 0},
/*.*/ {0, 0, 0, 0, 0, 0, D, 0},
/*,*/ {0, 0, 0, 0, 0, E, E, D},
/*:*/ {0, 0, 0, 0, D, 0, D, 0},
/*!*/ {D, D, D, D, D, 0, D, 0},
/*/ */ {G, F, E, D, C, B, A, 0},
/*\\*/ {A, B, C, D, E, F, G, 0},
/*|*/ {D, D, D, D, D, D, D, D},
/*+*/ {0, D, D, B|C|D|E|F, D, D, 0, 0},
/*-*/ {0, 0, 0, B|C|D|E|F, 0, 0, 0, 0},
/***/ {0, B|D|F, C|D|E, D, C|D|E, B|D|F, 0, 0},
/*=*/ {0, 0, B|C|D|E|F, 0, B|C|D|E|F, 0, 0, 0}
};
int enc(int c) { return strchr(vec,c)-vec; }
void show(char *s) {
int row,col;
char *sp;
for (row=0; row<8; row++, putchar('\n'))
for (sp = s; *sp; sp++)
if (strchr(vec,*sp)!=NULL)
for (col=0; col<8; col++)
putchar(map[enc(*sp)][row] & 1<<col ? *sp:' ');
}
int main(int c,char **v) {
for (--c,++v;*v;v++,c--) show(*v);
return 0;
}
/*
01234567 01234567 01234567 01234567 01234567 01234567
0 ##### # ### #
1 # # # # #
2 # # #### # # #### # #
3 ##### # ##### ##### # # ####
4 # # ##### # # # # # # #
5 # # # # # # # #### # #
6 ##### #### # # #### # # ## #
7 ####
*/
/*
01234567 01234567 01234567 01234567 01234567 01234567
0 #
1 # # # #
2 # # # ##### #### #
3 ## # ## ### ## # # # #
4 # # # # # # # # # # #
5 # # # # # # # #### ####
6 ##### # # ## ## ## # # # #
7 ## ## ##
*/
/*
01234567 01234567 01234567 01234567 01234567 01234567
0
1
2 ## ## #### # # # # ###### # #
3 ## # # # # # # # # #
4 # #### ## # # # # # #
5 # # # # # # # # # #
6 ## ##### # # # ## ###### ## ##
7 ###
*/
/*
01234567 01234567 01234567 01234567 01234567 01234567
0 # ##### ### #### ##### # #
1 # # # # # # # # # # #
2 # # # # # # # # # #
3 # # ##### # # # # # #
4 ##### # # # # # # # # #
5 # # # # # # # # # # # # #
6 # # ##### ### #### # # # #
7 #
*/
