Raw read/write Functions (Using the GNU Compiler Collection (GCC))

#### 7.13.11.4 Raw Read/Write Functions ¶

This sections describes built-in functions related to read and write instructions to access memory. These functions generate `membar` instructions to flush the I/O load and stores where appropriate, as described in Fujitsu’s manual described above.

`unsigned char __builtin_read8 (void *data)`
`unsigned short __builtin_read16 (void *data)`
`unsigned long __builtin_read32 (void *data)`
`unsigned long long __builtin_read64 (void *data)`
`void __builtin_write8 (void *data, unsigned char datum)`
`void __builtin_write16 (void *data, unsigned short datum)`
`void __builtin_write32 (void *data, unsigned long datum)`
`void __builtin_write64 (void *data, unsigned long long datum)`