- DOUBLE pow2_i; /* = pow2[i] */
- DOUBLE powh_i; /* = powh[i] */
-
- /* Invariants: pow2_i = 2^2^i, powh_i = 2^-2^i,
- x * 2^exponent = argument, x < 1.0, exponent >= MIN_EXP - 1. */
- for (i = 0, pow2_i = L_(2.0), powh_i = L_(0.5);
- ;
- i++, pow2_i = pow2_i * pow2_i, powh_i = powh_i * powh_i)
- {
- if (exponent - (1 << i) < MIN_EXP - 1)
- break;
-
- exponent -= (1 << i);
- x *= pow2_i;
- if (x >= L_(1.0))
- break;
-
- pow2[i] = pow2_i;
- powh[i] = powh_i;
- }
+ /* A negative exponent. */
+ {
+ DOUBLE pow2_i; /* = pow2[i] */
+ DOUBLE powh_i; /* = powh[i] */
+
+ /* Invariants: pow2_i = 2^2^i, powh_i = 2^-2^i,
+ x * 2^exponent = argument, x < 1.0, exponent >= MIN_EXP - 1. */
+ for (i = 0, pow2_i = L_(2.0), powh_i = L_(0.5);
+ ;
+ i++, pow2_i = pow2_i * pow2_i, powh_i = powh_i * powh_i)
+ {
+ if (exponent - (1 << i) < MIN_EXP - 1)
+ break;
+
+ exponent -= (1 << i);
+ x *= pow2_i;
+ if (x >= L_(1.0))
+ break;
+
+ pow2[i] = pow2_i;
+ powh[i] = powh_i;
+ }
+ }
+ /* Here either x < 1.0 and exponent - 2^i < MIN_EXP - 1 <= exponent,
+ or 1.0 <= x < 2^2^i and exponent >= MIN_EXP - 1. */
+
+ if (x < L_(1.0))
+ /* Invariants: x * 2^exponent = argument, x < 1.0 and
+ exponent - 2^i < MIN_EXP - 1 <= exponent. */
+ while (i > 0)
+ {
+ i--;
+ if (exponent - (1 << i) >= MIN_EXP - 1)
+ {
+ exponent -= (1 << i);
+ x *= pow2[i];
+ if (x >= L_(1.0))
+ break;
+ }
+ }
+
+ /* Here either x < 1.0 and exponent = MIN_EXP - 1,
+ or 1.0 <= x < 2^2^i and exponent >= MIN_EXP - 1. */