Generate Full ASCII-Chart in Single Loop

/* simple program to generate a full ASCII-chart on stdout */
#include <stdio.h>

enum { TWO = 1u << 1, R1 = 1u << 5, R2 = 1u << 6, R3 = R1 + R2 };

int main (void) {

    char *special[] = { "(nul)", "(soh)", "(stx)", "(etx)",
                        "(eot)", "(enq)", "(ack)", "(bel)",
                        "(bs)",  "(ht)",  "(nl)",  "(vt)",
                        "(np)",  "(cr)",  "(so)",  "(si)",
                        "(dle)", "(dc1)", "(dc2)", "(dc3)",
                        "(dc4)", "(nak)", "(syn)", "(etb)",
                        "(can)", "(em)",  "(sub)", "(esc)",
                        "(fs)",  "(gs)",  "(rs)",  "(us)",
                        "(sp)",  "(del)" };

    /* print heading */
    printf ("Char  Dec  Oct  Hex | Char  Dec  Oct  Hex | "
            "Char  Dec  Oct  Hex | Char  Dec  Oct  Hex\n"
            "--------------------------------------------"
            "-----------------------------------------\n");

    /* print chars */
    for (unsigned i = 0; i < R1; i++) {
        char s1[TWO] = { (char)i+R1, 0 },
             s2[TWO] = { (char)i+R2, 0 },
             s3[TWO] = { (char)i+R3, 0 };

        printf ("%-5s %3d %04o 0x%02x | %-5s %3d %04o 0x%02x | "
                "%-5s %3d %04o 0x%02x | %-5s %3d %04o 0x%02x\n",
                special[i], i, i, i,
                i ? s1 : special[R1], i+R1, i+R1, i+R1,
                s2, i+R2, i+R2, i+R2,
                i == R1 - 1 ? special[R1+1] : s3, i+R3, i+R3, i+R3);
    }

    return 0;
}