diff options
Diffstat (limited to 'xserver/include/misc.h')
| -rw-r--r-- | xserver/include/misc.h | 121 |
1 files changed, 59 insertions, 62 deletions
diff --git a/xserver/include/misc.h b/xserver/include/misc.h index 2dedf6d63..546ed5c96 100644 --- a/xserver/include/misc.h +++ b/xserver/include/misc.h @@ -128,21 +128,6 @@ typedef struct _xReq *xReqPtr; #define USE_BACKGROUND_PIXEL 3 #define USE_BORDER_PIXEL 3 -/* byte swap a 32-bit literal */ -static inline uint32_t -lswapl(uint32_t x) -{ - return ((x & 0xff) << 24) | - ((x & 0xff00) << 8) | ((x & 0xff0000) >> 8) | ((x >> 24) & 0xff); -} - -/* byte swap a 16-bit literal */ -static inline uint16_t -lswaps(uint16_t x) -{ - return (uint16_t)((x & 0xff) << 8) | ((x >> 8) & 0xff); -} - #undef min #undef max @@ -311,88 +296,100 @@ __builtin_constant_p(int x) } #endif -/* byte swap a 64-bit value */ -static inline void -swap_uint64(uint64_t *x) +#ifndef bswap_64 +static inline uint64_t +bswap_64(uint64_t x) { - char n; - - n = ((char *) x)[0]; - ((char *) x)[0] = ((char *) x)[7]; - ((char *) x)[7] = n; - - n = ((char *) x)[1]; - ((char *) x)[1] = ((char *) x)[6]; - ((char *) x)[6] = n; - - n = ((char *) x)[2]; - ((char *) x)[2] = ((char *) x)[5]; - ((char *) x)[5] = n; - - n = ((char *) x)[3]; - ((char *) x)[3] = ((char *) x)[4]; - ((char *) x)[4] = n; + return (((x & 0xFF00000000000000ull) >> 56) | + ((x & 0x00FF000000000000ull) >> 40) | + ((x & 0x0000FF0000000000ull) >> 24) | + ((x & 0x000000FF00000000ull) >> 8) | + ((x & 0x00000000FF000000ull) << 8) | + ((x & 0x0000000000FF0000ull) << 24) | + ((x & 0x000000000000FF00ull) << 40) | + ((x & 0x00000000000000FFull) << 56)); } +#endif #define swapll(x) do { \ if (sizeof(*(x)) != 8) \ wrong_size(); \ - swap_uint64((uint64_t *)(x)); \ + *(x) = bswap_64(*(x)); \ } while (0) -/* byte swap a 32-bit value */ -static inline void -swap_uint32(uint32_t * x) +#ifndef bswap_32 +static inline uint32_t +bswap_32(uint32_t x) +{ + return (((x & 0xFF000000) >> 24) | + ((x & 0x00FF0000) >> 8) | + ((x & 0x0000FF00) << 8) | + ((x & 0x000000FF) << 24)); +} +#endif + +static inline Bool +checked_int64_add(int64_t *out, int64_t a, int64_t b) +{ + /* Do the potentially overflowing math as uint64_t, as signed + * integers in C are undefined on overflow (and the compiler may + * optimize out our overflow check below, otherwise) + */ + int64_t result = (uint64_t)a + (uint64_t)b; + /* signed addition overflows if operands have the same sign, and + * the sign of the result doesn't match the sign of the inputs. + */ + Bool overflow = (a < 0) == (b < 0) && (a < 0) != (result < 0); + + *out = result; + + return overflow; +} + +static inline Bool +checked_int64_subtract(int64_t *out, int64_t a, int64_t b) { - char n = ((char *) x)[0]; + int64_t result = (uint64_t)a - (uint64_t)b; + Bool overflow = (a < 0) != (b < 0) && (a < 0) != (result < 0); - ((char *) x)[0] = ((char *) x)[3]; - ((char *) x)[3] = n; - n = ((char *) x)[1]; - ((char *) x)[1] = ((char *) x)[2]; - ((char *) x)[2] = n; + *out = result; + + return overflow; } #define swapl(x) do { \ if (sizeof(*(x)) != 4) \ wrong_size(); \ - if (__builtin_constant_p((uintptr_t)(x) & 3) && ((uintptr_t)(x) & 3) == 0) \ - *(x) = lswapl(*(x)); \ - else \ - swap_uint32((uint32_t *)(x)); \ + *(x) = bswap_32(*(x)); \ } while (0) -/* byte swap a 16-bit value */ -static inline void -swap_uint16(uint16_t * x) +#ifndef bswap_16 +static inline uint16_t +bswap_16(uint16_t x) { - char n = ((char *) x)[0]; - - ((char *) x)[0] = ((char *) x)[1]; - ((char *) x)[1] = n; + return (((x & 0xFF00) >> 8) | + ((x & 0x00FF) << 8)); } +#endif #define swaps(x) do { \ if (sizeof(*(x)) != 2) \ wrong_size(); \ - if (__builtin_constant_p((uintptr_t)(x) & 1) && ((uintptr_t)(x) & 1) == 0) \ - *(x) = lswaps(*(x)); \ - else \ - swap_uint16((uint16_t *)(x)); \ + *(x) = bswap_16(*(x)); \ } while (0) /* copy 32-bit value from src to dst byteswapping on the way */ #define cpswapl(src, dst) do { \ if (sizeof((src)) != 4 || sizeof((dst)) != 4) \ wrong_size(); \ - (dst) = lswapl((src)); \ + (dst) = bswap_32((src)); \ } while (0) /* copy short from src to dst byteswapping on the way */ #define cpswaps(src, dst) do { \ if (sizeof((src)) != 2 || sizeof((dst)) != 2) \ wrong_size(); \ - (dst) = lswaps((src)); \ + (dst) = bswap_16((src)); \ } while (0) extern _X_EXPORT void SwapLongs(CARD32 *list, unsigned long count); |