## OilFunctionImpl

OilFunctionImpl — Functions for manipulating function implementations.

## Synopsis

                        OilFunctionImpl;
    OilFunctionImpl *   oil_impl_get_by_index               (int i);
    int                 oil_impl_is_runnable                (OilFunctionImpl *impl);
    enum                OilImplFlag;
    #define             OIL_CPU_FLAG_MASK
    #define             OIL_DEFINE_IMPL_FULL                (function,klass,flags)
    #define             OIL_DEFINE_IMPL                     (function,klass)
    #define             OIL_DEFINE_IMPL_REF                 (function,klass)
    #define             OIL_DEFINE_IMPL_ASM                 (function,klass)
    #define             OIL_DEFINE_IMPL_DEPENDS             (function,klass,...)

## Description

## Details

### OilFunctionImpl

    typedef struct {
    } OilFunctionImpl;

An opaque structure representing a function implementation.

### oil_impl_get_by_index ()

    OilFunctionImpl *   oil_impl_get_by_index               (int i);

Returns a pointer to the function implementation with index `i`.

`i` : | index
Returns : | a pointer to a function implementation structure

### oil_impl_is_runnable ()

    int                 oil_impl_is_runnable                (OilFunctionImpl *impl);

Determines whether the function implementation given by `impl` can be executed by the current CPU.

`impl` : | an `OilFunctionImpl`
Returns : | 1 if the implementation can be executed, otherwise 0

### enum OilImplFlag

    typedef enum {
      OIL_IMPL_FLAG_REF = (1<<0),
      OIL_IMPL_FLAG_OPT = (1<<1),
      OIL_IMPL_FLAG_ASM = (1<<2),
      OIL_IMPL_FLAG_DISABLED = (1<<3),
      OIL_IMPL_FLAG_CMOV = (1<<16),
      OIL_IMPL_FLAG_MMX = (1<<17),
      OIL_IMPL_FLAG_SSE = (1<<18),
      OIL_IMPL_FLAG_MMXEXT = (1<<19),
      OIL_IMPL_FLAG_SSE2 = (1<<20),
      OIL_IMPL_FLAG_3DNOW = (1<<21),
      OIL_IMPL_FLAG_3DNOWEXT = (1<<22),
      OIL_IMPL_FLAG_SSE3 = (1<<23),
      OIL_IMPL_FLAG_ALTIVEC = (1<<24),
      OIL_IMPL_FLAG_EDSP = (1<<25),
      OIL_IMPL_FLAG_ARM6 = (1<<26),
      OIL_IMPL_FLAG_VFP = (1<<27),
      OIL_IMPL_FLAG_SSSE3 = (1<<28)
    } OilImplFlag;

Implementation flags.

`OIL_IMPL_FLAG_REF`: is the reference implementation for the class.

`OIL_IMPL_FLAG_OPT`: was compiled with alternate CFLAGS as specified by --enable-alternate-optimization.

`OIL_IMPL_FLAG_ASM`: is written in assembly code.

`OIL_IMPL_FLAG_DISABLED`: is disabled. This can be set either in the source code or during library initialization.

`OIL_IMPL_FLAG_CMOV`: uses the i386 instruction cmov or its variants.

`OIL_IMPL_FLAG_MMX`: uses MMX instructions.

`OIL_IMPL_FLAG_SSE`: uses SSE instructions.

`OIL_IMPL_FLAG_MMXEXT`: uses AMD's extended MMX instructions. These are a subset of what Intel calls SSE2. If an implementation uses only AMD's extended MMX instructions, it should set this flag, and not `OIL_IMPL_FLAG_SSE2`.

`OIL_IMPL_FLAG_SSE2`: uses SSE2 instructions. This flag implies `OIL_IMPL_FLAG_SSE` and `OIL_IMPL_FLAG_MMXEXT`.

`OIL_IMPL_FLAG_3DNOW`: uses 3DNow! instructions.

`OIL_IMPL_FLAG_3DNOWEXT`: uses extended 3DNow! instructions.

`OIL_IMPL_FLAG_SSE3`: uses SSE3 instructions. This flag implies `OIL_IMPL_FLAG_SSE2`.

`OIL_IMPL_FLAG_SSSE3`: uses SSSE3 instructions. This flag implies `OIL_IMPL_FLAG_SSE3`.

`OIL_IMPL_FLAG_ALTIVEC`: uses Altivec instructions.

### OIL_CPU_FLAG_MASK

    #define OIL_CPU_FLAG_MASK 0xffff0000

Mask describing which bits in OilImplFlag depend on the current CPU.

### OIL_DEFINE_IMPL_FULL()

    #define             OIL_DEFINE_IMPL_FULL(function,klass,flags)

Defines a OilFunctionImpl structure for the function `function` and class `klass`. CPU-dependent flags in `flags` will indicate that this implementation requires the given CPU flags.

`function` : | name of function
`klass` : | name of class to declare (without oil_ prefix)
`flags` : | implementation flags and CPU requirements

### OIL_DEFINE_IMPL()

    #define             OIL_DEFINE_IMPL(function,klass)

Shorthand for defining a C implementation. See `OIL_DEFINE_IMPL_FULL()`.

`function` : | name of function
`klass` : | name of class to declare (without oil_ prefix)

### OIL_DEFINE_IMPL_REF()

    #define             OIL_DEFINE_IMPL_REF(function,klass)

Shorthand for defining a reference implementation. See `OIL_DEFINE_IMPL_FULL()`.

`function` : | name of function
`klass` : | name of class to declare (without oil_ prefix)

### OIL_DEFINE_IMPL_ASM()

    #define             OIL_DEFINE_IMPL_ASM(function,klass)

Shorthand for defining an implementation written in inline assembly code. See `OIL_DEFINE_IMPL_FULL()`.

`function` : | name of function
`klass` : | name of class to declare (without oil_ prefix)

### OIL_DEFINE_IMPL_DEPENDS()

    #define             OIL_DEFINE_IMPL_DEPENDS(function,klass,...)

Shorthand for defining an implementation that uses another Liboil function class. This is not currently used. See `OIL_DEFINE_IMPL_FULL()`.

`function` : | name of function
`klass` : | name of class to declare (without oil_ prefix)
`...` : | other classes this implementation uses