1 //===-- lib/builtins/ppc/fixunstfti.c - Convert long double->int128 *-C -*-===//
9 // This file implements converting the 128bit IBM/PowerPC long double (double-
10 // double) data type to an unsigned 128 bit integer.
17 // Convert long double into an unsigned 128-bit integer.
18 __uint128_t __fixunstfti(long double input) {  in __fixunstfti()
28   // The long double representation, with the high and low portions of  in __fixunstfti()
29   // the long double, and the corresponding bit patterns of each double.  in __fixunstfti()
31     long double ld;  in __fixunstfti()
32     double d[2];               // [0] is the high double, [1] is the low double.  in __fixunstfti()
36   // If the long double is less than 1.0 or negative,  in __fixunstfti()
49   // Convert each double into int64; they will be added to the int128 result.  in __fixunstfti()
50   // CASE 1: High or low double fits in int64  in __fixunstfti()
51   //      - Convert the each double normally into int64.  in __fixunstfti()
53   // CASE 2: High or low double does not fit in int64  in __fixunstfti()
54   //      - Scale the double to fit within a 64-bit integer  in __fixunstfti()
55   //      - Calculate the shift (amount to scale the double by in the int128)  in __fixunstfti()
58   //      - Scale (move) the double to the correct place in the int128  in __fixunstfti()
61   // Note: If the high double is assumed to be positive, an unsigned conversion  in __fixunstfti()
62   // from long double to 64-bit integer is needed. The low double can be either  in __fixunstfti()
64   // of the low double and to ensure it does not simply get converted to 0.  in __fixunstfti()
66   // CASE 1 - High double fits in int64.  in __fixunstfti()
70     // CASE 2 - High double does not fit in int64, scale and convert it.  in __fixunstfti()
78     // double is greater than 128 bits and when the long double  in __fixunstfti()
90   // CASE 1 - Low double fits in int64.  in __fixunstfti()
94     // CASE 2 - Low double does not fit in int64, scale and convert it.  in __fixunstfti()
102   // If the low double is negative, it may change the integer value of the  in __fixunstfti()
104   // the fractional part of the high double. Because both doubles cannot  in __fixunstfti()
105   // overlap, this situation only occurs when the high double has no  in __fixunstfti()
108   if ((ldUnion.d[0] == (double)hiResult) &&  in __fixunstfti()
109       (ldUnion.d[1] < (double)((__int128_t)loResult)))  in __fixunstfti()