#### 6.58.3 Altera Nios II Built-in Functions

These built-in functions are available for the Altera Nios II family of processors.

The following built-in functions are always available. They all generate the machine instruction that is part of the name.

         int __builtin_ldbio (volatile const void *)
         int __builtin_ldbuio (volatile const void *)
         int __builtin_ldhio (volatile const void *)
         int __builtin_ldhuio (volatile const void *)
         int __builtin_ldwio (volatile const void *)
         void __builtin_stbio (volatile void *, int)
         void __builtin_sthio (volatile void *, int)
         void __builtin_stwio (volatile void *, int)
         void __builtin_sync (void)
         int __builtin_rdctl (int)
         void __builtin_wrctl (int, int)

The following built-in functions are always available. They all generate a Nios II Custom Instruction. The name of the function represents the types that the function takes and returns. The letter before the `n` is the return type or void if absent. The `n` represents the first parameter to all the custom instructions, the custom instruction number. The two letters after the `n` represent the up to two parameters to the function.

The letters represent the following data types:

`<no letter>`
  `void` for return type and no parameter for parameter types.
`i`
  `int` for return type and parameter type
`f`
  `float` for return type and parameter type
`p`
  `void *` for return type and parameter type

And the function names are:

         void __builtin_custom_n (void)
         void __builtin_custom_ni (int)
         void __builtin_custom_nf (float)
         void __builtin_custom_np (void *)
         void __builtin_custom_nii (int, int)
         void __builtin_custom_nif (int, float)
         void __builtin_custom_nip (int, void *)
         void __builtin_custom_nfi (float, int)
         void __builtin_custom_nff (float, float)
         void __builtin_custom_nfp (float, void *)
         void __builtin_custom_npi (void *, int)
         void __builtin_custom_npf (void *, float)
         void __builtin_custom_npp (void *, void *)
         int __builtin_custom_in (void)
         int __builtin_custom_ini (int)
         int __builtin_custom_inf (float)
         int __builtin_custom_inp (void *)
         int __builtin_custom_inii (int, int)
         int __builtin_custom_inif (int, float)
         int __builtin_custom_inip (int, void *)
         int __builtin_custom_infi (float, int)
         int __builtin_custom_inff (float, float)
         int __builtin_custom_infp (float, void *)
         int __builtin_custom_inpi (void *, int)
         int __builtin_custom_inpf (void *, float)
         int __builtin_custom_inpp (void *, void *)
         float __builtin_custom_fn (void)
         float __builtin_custom_fni (int)
         float __builtin_custom_fnf (float)
         float __builtin_custom_fnp (void *)
         float __builtin_custom_fnii (int, int)
         float __builtin_custom_fnif (int, float)
         float __builtin_custom_fnip (int, void *)
         float __builtin_custom_fnfi (float, int)
         float __builtin_custom_fnff (float, float)
         float __builtin_custom_fnfp (float, void *)
         float __builtin_custom_fnpi (void *, int)
         float __builtin_custom_fnpf (void *, float)
         float __builtin_custom_fnpp (void *, void *)
         void * __builtin_custom_pn (void)
         void * __builtin_custom_pni (int)
         void * __builtin_custom_pnf (float)
         void * __builtin_custom_pnp (void *)
         void * __builtin_custom_pnii (int, int)
         void * __builtin_custom_pnif (int, float)
         void * __builtin_custom_pnip (int, void *)
         void * __builtin_custom_pnfi (float, int)
         void * __builtin_custom_pnff (float, float)
         void * __builtin_custom_pnfp (float, void *)
         void * __builtin_custom_pnpi (void *, int)
         void * __builtin_custom_pnpf (void *, float)
         void * __builtin_custom_pnpp (void *, void *)