diff options
Diffstat (limited to 'src/mpfr-impl.h')
| -rw-r--r-- | src/mpfr-impl.h | 21 |
1 files changed, 15 insertions, 6 deletions
diff --git a/src/mpfr-impl.h b/src/mpfr-impl.h index 5ea624af1..b24975491 100644 --- a/src/mpfr-impl.h +++ b/src/mpfr-impl.h @@ -1173,18 +1173,27 @@ typedef uintmax_t mpfr_ueexp_t; /* Mask for the low 's' bits of a limb */ #define MPFR_LIMB_MASK(s) ((MPFR_LIMB_ONE << (s)) - MPFR_LIMB_ONE) -/* Cast to mp_limb_t, assuming that x is based on mp_limb_t variables - (needed when mp_limb_t is defined as an integer type shorter than - int, due to the integer promotion rules, which is possible only +/* MPFR_LIMB: Cast to mp_limb_t, assuming that x is based on mp_limb_t + variables (needed when mp_limb_t is defined as an integer type shorter + than int, due to the integer promotion rules, which is possible only if MPFR_LONG_WITHIN_LIMB is not defined). Warning! This will work only when the computed value x is congruent to the expected value - modulo MPFR_LIMB_MAX + 1. Be aware that this macro may not solve - all the problems related to the integer promotion rules, because - it won't have an influence on the evaluation of x itself. */ + modulo MPFR_LIMB_MAX + 1. Be aware that this macro may not solve all + the problems related to the integer promotion rules, because it won't + have an influence on the evaluation of x itself. Hence the need for... + + MPFR_LIMB_LSHIFT: Left shift by making sure that the shifted argument + is unsigned (use unsigned long due to the MPFR_LONG_WITHIN_LIMB test). + For instance, due to the integer promotion rules, if mp_limb_t is + defined as a 16-bit unsigned short and an int has 32 bits, then a + mp_limb_t will be converted to an int, which is signed. +*/ #ifdef MPFR_LONG_WITHIN_LIMB #define MPFR_LIMB(x) (x) +#define MPFR_LIMB_LSHIFT(x,c) ((x) << (c)) #else #define MPFR_LIMB(x) ((mp_limb_t) (x)) +#define MPFR_LIMB_LSHIFT(x,c) MPFR_LIMB((unsigned long) (x) << (c)) #endif /****************************************************** |