------------------------------------------------------------------------------ -- -- -- GNAT COMPILER COMPONENTS -- -- -- -- G N A T . A L T I V E C -- -- -- -- S p e c -- -- -- -- Copyright (C) 2004-2006, Free Software Foundation, Inc. -- -- -- -- GNAT is free software; you can redistribute it and/or modify it under -- -- terms of the GNU General Public License as published by the Free Soft- -- -- ware Foundation; either version 2, or (at your option) any later ver- -- -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- -- for more details. You should have received a copy of the GNU General -- -- Public License distributed with GNAT; see file COPYING. If not, write -- -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, -- -- MA 02111-1307, USA. -- -- -- -- As a special exception, if other files instantiate generics from this -- -- unit, or you link this unit with other files to produce an executable, -- -- this unit does not by itself cause the resulting executable to be -- -- covered by the GNU General Public License. This exception does not -- -- however invalidate any other reasons why the executable file might be -- -- covered by the GNU Public License. -- -- -- -- GNAT was originally developed by the GNAT team at New York University. -- -- Extensive contributions were provided by Ada Core Technologies Inc. -- -- -- ------------------------------------------------------------------------------ ------------------------- -- General description -- ------------------------- -- This is the root of a package hierarchy offering an Ada binding to the -- PowerPC AltiVec extensions. These extensions basically consist in a set of -- 128bit vector types together with a set of subprograms operating on such -- vectors. On a real Altivec capable target, vector objects map to hardware -- vector registers and the subprograms map to a set of specific hardware -- instructions. -- Relevant documents are: -- o AltiVec Technology, Programming Interface Manual (1999-06) -- to which we will refer as [PIM], describes the data types, the -- functional interface and the ABI conventions. -- o AltiVec Technology, Programming Environments Manual (2002-02) -- to which we will refer as [PEM], describes the hardware architecture -- and instruction set. -- These documents, as well as a number of others of general interest on the -- AltiVec technology, are available from the Motorola/AltiVec Web site at -- http://www.motorola.com/altivec -- We offer two versions of this binding: one for real AltiVec capable -- targets, and one for other targets. In the latter case, everything is -- emulated in software. We will refer to the two bindings as: -- o The Hard binding for AltiVec capable targets (with the appropriate -- hardware support and corresponding instruction set) -- o The Soft binding for other targets (with the low level primitives -- emulated in software). -- The two versions of the binding are expected to be equivalent from the -- functional standpoint. The same client application code should observe no -- difference in operation results, even if the Soft version is used on a -- non-powerpc target. The Hard binding is naturally expected to run faster -- than the Soft version on the same target. -- We also offer interfaces not strictly part of the base AltiVec API, such -- as vector conversions to/from array representations, which are of interest -- for client applications (e.g. for vector initialization purposes) and may -- also be used as implementation facilities. ----------------------------------------- -- General package architecture survey -- ----------------------------------------- -- The various vector representations are all "containers" of elementary -- values, the possible types of which are declared in this root package to -- be generally accessible. -- From the user standpoint, the two versions of the binding are available -- through a consistent hierarchy of units providing identical services: -- GNAT.Altivec -- (component types) -- | -- o----------------o----------------o-------------o -- | | | | -- Vector_Types Vector_Operations Vector_Views Conversions -- The user can manipulate vectors through two families of types: Vector -- types and View types. -- Vector types are defined in the GNAT.Altivec.Vector_Types package -- On these types, the user can apply the Altivec operations defined in -- GNAT.Altivec.Vector_Operations. Their layout is opaque and may vary across -- configurations, for it is typically target-endianness dependant. -- Vector_Types and Vector_Operations implement the core binding to the -- AltiVec API, as described in [PIM-2.1 data types] and [PIM-4 AltiVec -- operations and predicates]. -- View types are defined in the GNAT.Altivec.Vector_Views package -- These types do not represent Altivec vectors per se, in the sense that the -- Altivec_Operations are not available for them. They are intended to allow -- Vector initializations as well as access to the Vector component values. -- The GNAT.Altivec.Conversions package is provided to convert a View to the -- corresponding Vector and vice-versa. -- The two versions of the binding rely on a low level internal interface, -- and switching from one version to the other amounts to select one low -- level implementation instead of the other. -- The bindings are provided as a set of sources together with a project file -- (altivec.gpr). The hard/soft binding selection is controlled by a project -- variable on targets where switching makes sense. See the example usage -- section below. --------------------------- -- Underlying principles -- --------------------------- -- The general organization sketched above has been devised from a number -- of driving ideas: -- o From the clients standpoint, the two versions of the binding should be -- as easily exchangable as possible, -- o From the maintenance standpoint, we want to avoid as much code -- duplication as possible. -- o From both standpoints above, we want to maintain a clear interface -- separation between the base bindings to the Motorola API and the -- additional facilities. -- The identification of the low level interface is directly inspired by the -- the base API organization, basically consisting of a rich set of functions -- around a core of low level primitives mapping to AltiVec instructions. -- See for instance "vec_add" in [PIM-4.4 Generic and Specific AltiVec -- operations]: no less than six result/arguments combinations of byte vector -- types map to "vaddubm". -- The "hard" version of the low level primitives map to real AltiVec -- instructions via the corresponding GCC builtins. The "soft" version is -- a software emulation of those. ------------------- -- Example usage -- ------------------- -- Here is a sample program declaring and initializing two vectors, 'add'ing -- them and displaying the result components: -- with GNAT.Altivec.Vector_Types; use GNAT.Altivec.Vector_Types; -- with GNAT.Altivec.Vector_Operations; use GNAT.Altivec.Vector_Operations; -- with GNAT.Altivec.Vector_Views; use GNAT.Altivec.Vector_Views; -- with GNAT.Altivec.Conversions; use GNAT.Altivec.Conversions; -- use GNAT.Altivec; -- procedure Sample is -- Va : Vector_Unsigned_Int := To_Vector ((Values => (1, 2, 3, 4))); -- Vb : Vector_Unsigned_Int := To_Vector ((Values => (1, 2, 3, 4))); -- Vs : Vector_Unsigned_Int; -- Vs_View : VUI_View; -- begin -- Vs := Vec_Add (Va, Vb); -- Vs_View := To_View (Vs); -- for I in Vs_View.Values'Range loop -- Put_Line (Unsigned_Int'Image (Vs_View.Values (I))); -- end loop; -- end; -- This currently requires the GNAT project management facilities to compile, -- to automatically retrieve the set of necessary sources and switches -- depending on your configuration. For the example above, customizing the -- switches to include -g also, this would be something like: -- sample.gpr -- -- with "altivec.gpr"; -- -- project Sample is -- for Source_Dirs use ("."); -- for Main use ("sample"); -- package Compiler is -- for Default_Switches ("Ada") use -- Altivec.Compiler'Default_Switches ("Ada") & "-g"; -- end Compiler; -- end Sample; -- $ gnatmake -Psample -- [...] -- $ ./sample -- 2 -- 4 -- 6 -- 8 ------------------------------------------------------------------------------ with System; package GNAT.Altivec is -- Definitions of constants and vector/array component types common to all -- the versions of the binding. -- All the vector types are 128bits VECTOR_BIT : constant := 128; ------------------------------------------- -- [PIM-2.3.1 Alignment of vector types] -- ------------------------------------------- -- "A defined data item of any vector data type in memory is always -- aligned on a 16-byte boundary. A pointer to any vector data type always -- points to a 16-byte boundary. The compiler is responsible for aligning -- vector data types on 16-byte boundaries." VECTOR_ALIGNMENT : constant := Natural'Min (16, Standard'Maximum_Alignment); -- This value is used to set the alignment of vector datatypes in both the -- hard and the soft binding implementations. -- -- We want this value to never be greater than 16, because none of the -- binding implementations requires larger alignments and such a value -- would cause useless space to be allocated/wasted for vector objects. -- Furthermore, the alignment of 16 matches the hard binding leading to -- a more faithful emulation. -- -- It needs to be exactly 16 for the hard binding, and the initializing -- expression is just right for this purpose since Maximum_Alignment is -- expected to be 16 for the real Altivec ABI. -- -- The soft binding doesn't rely on strict 16byte alignment, and we want -- the value to be no greater than Standard'Maximum_Alignment in this case -- to ensure it is supported on every possible target. ------------------------------------------------------- -- [PIM-2.1] Data Types - Interpretation of contents -- ------------------------------------------------------- --------------------- -- char components -- --------------------- CHAR_BIT : constant := 8; SCHAR_MIN : constant := -2 ** (CHAR_BIT - 1); SCHAR_MAX : constant := 2 ** (CHAR_BIT - 1) - 1; UCHAR_MAX : constant := 2 ** CHAR_BIT - 1; type unsigned_char is mod UCHAR_MAX + 1; for unsigned_char'Size use CHAR_BIT; type signed_char is range SCHAR_MIN .. SCHAR_MAX; for signed_char'Size use CHAR_BIT; subtype bool_char is unsigned_char; -- ??? There is a difference here between what the Altivec Technology -- Programming Interface Manual says and what GCC says. In the manual, -- vector_bool_char is a vector_unsigned_char, while in altivec.h it -- is a vector_signed_char. bool_char_True : constant bool_char := bool_char'Last; bool_char_False : constant bool_char := 0; ---------------------- -- short components -- ---------------------- SHORT_BIT : constant := 16; SSHORT_MIN : constant := -2 ** (SHORT_BIT - 1); SSHORT_MAX : constant := 2 ** (SHORT_BIT - 1) - 1; USHORT_MAX : constant := 2 ** SHORT_BIT - 1; type unsigned_short is mod USHORT_MAX + 1; for unsigned_short'Size use SHORT_BIT; subtype unsigned_short_int is unsigned_short; type signed_short is range SSHORT_MIN .. SSHORT_MAX; for signed_short'Size use SHORT_BIT; subtype signed_short_int is signed_short; subtype bool_short is unsigned_short; -- ??? See bool_char bool_short_True : constant bool_short := bool_short'Last; bool_short_False : constant bool_short := 0; subtype bool_short_int is bool_short; -------------------- -- int components -- -------------------- INT_BIT : constant := 32; SINT_MIN : constant := -2 ** (INT_BIT - 1); SINT_MAX : constant := 2 ** (INT_BIT - 1) - 1; UINT_MAX : constant := 2 ** INT_BIT - 1; type unsigned_int is mod UINT_MAX + 1; for unsigned_int'Size use INT_BIT; type signed_int is range SINT_MIN .. SINT_MAX; for signed_int'Size use INT_BIT; subtype bool_int is unsigned_int; -- ??? See bool_char bool_int_True : constant bool_int := bool_int'Last; bool_int_False : constant bool_int := 0; ---------------------- -- float components -- ---------------------- FLOAT_BIT : constant := 32; FLOAT_DIGIT : constant := 6; FLOAT_MIN : constant := -16#0.FFFF_FF#E+32; FLOAT_MAX : constant := 16#0.FFFF_FF#E+32; type C_float is digits FLOAT_DIGIT range FLOAT_MIN .. FLOAT_MAX; for C_float'Size use FLOAT_BIT; ---------------------- -- pixel components -- ---------------------- subtype pixel is unsigned_short; ----------------------------------------------------------- -- Subtypes for variants found in the GCC implementation -- ----------------------------------------------------------- subtype c_int is signed_int; subtype c_short is c_int; LONG_BIT : constant := 32; -- Some of the GCC builtins are built with "long" arguments and -- expect SImode to come in. SLONG_MIN : constant := -2 ** (LONG_BIT - 1); SLONG_MAX : constant := 2 ** (LONG_BIT - 1) - 1; ULONG_MAX : constant := 2 ** LONG_BIT - 1; type signed_long is range SLONG_MIN .. SLONG_MAX; type unsigned_long is mod ULONG_MAX + 1; subtype c_long is signed_long; subtype c_ptr is System.Address; --------------------------------------------------------- -- Access types, for the sake of some argument passing -- --------------------------------------------------------- type signed_char_ptr is access all signed_char; type unsigned_char_ptr is access all unsigned_char; type short_ptr is access all c_short; type signed_short_ptr is access all signed_short; type unsigned_short_ptr is access all unsigned_short; type int_ptr is access all c_int; type signed_int_ptr is access all signed_int; type unsigned_int_ptr is access all unsigned_int; type long_ptr is access all c_long; type signed_long_ptr is access all signed_long; type unsigned_long_ptr is access all unsigned_long; type float_ptr is access all Float; -- type const_signed_char_ptr is access constant signed_char; type const_unsigned_char_ptr is access constant unsigned_char; type const_short_ptr is access constant c_short; type const_signed_short_ptr is access constant signed_short; type const_unsigned_short_ptr is access constant unsigned_short; type const_int_ptr is access constant c_int; type const_signed_int_ptr is access constant signed_int; type const_unsigned_int_ptr is access constant unsigned_int; type const_long_ptr is access constant c_long; type const_signed_long_ptr is access constant signed_long; type const_unsigned_long_ptr is access constant unsigned_long; type const_float_ptr is access constant Float; -- Access to const volatile arguments need specialized types type volatile_float is new Float; pragma Volatile (volatile_float); type volatile_signed_char is new signed_char; pragma Volatile (volatile_signed_char); type volatile_unsigned_char is new unsigned_char; pragma Volatile (volatile_unsigned_char); type volatile_signed_short is new signed_short; pragma Volatile (volatile_signed_short); type volatile_unsigned_short is new unsigned_short; pragma Volatile (volatile_unsigned_short); type volatile_signed_int is new signed_int; pragma Volatile (volatile_signed_int); type volatile_unsigned_int is new unsigned_int; pragma Volatile (volatile_unsigned_int); type volatile_signed_long is new signed_long; pragma Volatile (volatile_signed_long); type volatile_unsigned_long is new unsigned_long; pragma Volatile (volatile_unsigned_long); type constv_char_ptr is access constant volatile_signed_char; type constv_signed_char_ptr is access constant volatile_signed_char; type constv_unsigned_char_ptr is access constant volatile_unsigned_char; type constv_short_ptr is access constant volatile_signed_short; type constv_signed_short_ptr is access constant volatile_signed_short; type constv_unsigned_short_ptr is access constant volatile_unsigned_short; type constv_int_ptr is access constant volatile_signed_int; type constv_signed_int_ptr is access constant volatile_signed_int; type constv_unsigned_int_ptr is access constant volatile_unsigned_int; type constv_long_ptr is access constant volatile_signed_long; type constv_signed_long_ptr is access constant volatile_signed_long; type constv_unsigned_long_ptr is access constant volatile_unsigned_long; type constv_float_ptr is access constant volatile_float; private ----------------------- -- Various constants -- ----------------------- CR6_EQ : constant := 0; CR6_EQ_REV : constant := 1; CR6_LT : constant := 2; CR6_LT_REV : constant := 3; end GNAT.Altivec;