Loader's number

loader.c is an entry by Ralph Loader for the Bignum Bakeoff contest, whose objective is to write a program (in 512 characters or less) that generates the largest possible output.

The program diagonalizes over the Huet-Coquand calculus of constructions. Its output is defined as D5(99), where D(k) is the sum of all possible bit strings with a binary value of k or lower.

David Meows has shown that D(99) is larger than 2↑↑30419, and that even D2(99) would be much larger than fε 0 + ω3 (1000000) in the fast-growing hierarchy.

The final output of D5(99) is much larger than TREE(3) or SCG(13), although still vastly smaller than Rayo's number.

Code

 * 1) define R { return
 * 2) define P P (
 * 3) define L L (
 * 4) define T S (v, y, c,
 * 5) define C ),
 * 6) define X x)
 * 7) define F );}

int r, a; P y, X  R y - ~y << x; } Z (X  R r = x % 2 ? 0 : 1 + Z (x / 2 F L X   R x / 2 >> Z (x F T  t) { int f = L t C              x = r;   R         f - 2 ? f > 2 ? f - v ? t - (f > v) * c : y : P f, P T L X  C                           S (v+2, t  U y C  c, Z (X )))         :         A (T  L X  C                 T  Z (X ) F } A (y, X  R L y) - 1 ? 5 << P y, X      : S (4, x, 4, Z (r) F D (X {  int f,     d,      c = 0, t = 7, u = 14; while (x && D (x - 1 C B 1)) d = L L D (X ) C        f = L r C         x = L r C         c - r || (            L u) || L r) - f ||            B u = S (4, d, 4, r C                    t = A (t, d) C            f / 2 & B  c = P d, c C                               t  U t C                               u  U u) ) C        c && B            t = P               ~u & 2 | B                  u = 1 << P L c C  u) C                P L c C  t) C            c = r  C         u / 2 & B             c = P t, c C             u  U t C             t = 9 );   R a = P P t, P u, P x, c)) C                                 a F } main    R D (D (D (D (D (99)))) F
 * 1) define U = S(4,13,-4,
 * 1) define B (x /= 2) % 2 && (