static int int_pow(int i, int *exp_ptr) { int e, er, eq, j; int a, a1; /* renormalize */ a = i; e = POW_FRAC_BITS; while (a < (1 << (POW_FRAC_BITS - 1))) { a = a << 1; e--; } a -= (1 << POW_FRAC_BITS); a1 = 0; for(j = DEV_ORDER - 1; j >= 0; j--) a1 = POW_MULL(a, dev_4_3_coefs[j] + a1); a = (1 << POW_FRAC_BITS) + a1; /* exponent compute (exact) */ e = e * 4; er = e % 3; eq = e / 3; a = POW_MULL(a, pow_mult3[er]); while (a >= 2 * POW_FRAC_ONE) { a = a >> 1; eq++; } /* convert to float */ while (a < POW_FRAC_ONE) { a = a << 1; eq--; } /* now POW_FRAC_ONE <= a < 2 * POW_FRAC_ONE */ #if (POW_FRAC_BITS - 1) > FRAC_BITS a = (a + (1 << (POW_FRAC_BITS - FRAC_BITS - 1))) >> (POW_FRAC_BITS - FRAC_BITS); /* correct overflow */ if (a >= 2 * (1 << FRAC_BITS)) { a = a >> 1; eq++; } #endif *exp_ptr = eq; return a; }