/** @file    host.c
 ** @author  Andrea Vedaldi
 ** @brief   Host - Definition
 **/

/* AUTORIGHTS
 Copyright (C) 2007-09 Andrea Vedaldi and Brian Fulkerson

 This file is part of VLFeat, available in the terms of the GNU
 General Public License version 2.
 */

#include "host.h"
#include "generic.h"

/**
 @file host.h

 This module provides functionalities to identify the
 host operating system, C compiler,
 and CPU architecture. It also provides a few features
 to abstract from such details.

 - @ref host-os "Host operating system"
 - @ref host-compiler "Host compiler"
   - @ref host-compiler-data-model "Data models"
   - @ref host-compiler-other      "Oter compiler specific features"
 - @ref host-arch "Host CPU architecture"
   - @ref host-arch-endianness "Endianness"

 @see http://predef.sourceforge.net/index.php

 @section host-os Host operating system

 The module defines a symbol to identify the host operating system:
 ::VL_OS_WIN for Windows, ::VL_OS_LINUX for Linux, ::VL_OS_MACOSX for
 Mac OS X, and so on.

 @section host-compiler Host compiler

 The module defines a symbol to identify the host compiler:
 ::VL_COMPILER_MSC for Microsoft Visual C++, ::VL_COMPILER_GNUC for GNU C,
 and so on. The (integer) value of such symbols
 corresponds the version of the  compiler.

 The module defines a symbol to identify the data model of the compiler:
 ::VL_COMPILER_ILP32, ::VL_COMPILER_LP32, or ::VL_COMPILER_LP64 (see
 Sect. @ref host-compiler-data-model).
 For convenience, it also defines a number of atomic types of prescribed
 width (::vl_int8, ::vl_int16, ::vl_int32, etc.).

 @remark While some of such functionalities are provided by the
 standard header @c stdint.h, the latter is not supported
 by all platforms.

 @subsection host-compiler-data-model Data models

 The C language defines a number of atomic data types (such as @c char, @c short,
 @c int and so on). The number of bits (width)
 used to represent each data type depends on the compiler data model.
 The following table summarizes the relevant conventions:

 <table><caption><b>Compiler data models.</b> The table shows
 how many bits are allocated to each atomic data type according to
 each model.</caption>
 <tr style="font-weight:bold;">
 <td>Data model</td>
 <td><code>short</code></td>
 <td><code>int</code></td>
 <td><code>long</code></td>
 <td><code>long long</code></td>
 <td><code>void*</code></td>
 <td>Compiler</td>
 </tr>
 <tr>
 <td>ILP32</td>
 <td style="background-color:#ffa;">16</td>
 <td style="background-color:#afa;">32</td>
 <td style="background-color:#afa;">32</td>
 <td >64</td>
 <td style="background-color:#afa;">32</td>
 <td>common 32 bit architectures</td>
 </tr>
 <tr>
 <td>LP64</td>
 <td style="background-color:#ffa;">16</td>
 <td style="background-color:#afa;">32</td>
 <td>64</td>
 <td>64</td>
 <td>64</td>
 <td>UNIX-64 (Linux, Mac OS X)</td>
 </tr>
 <tr>
 <td>ILP64</td>
 <td style="background-color:#ffa;">16</td>
 <td>64</td>
 <td>64</td>
 <td>64</td>
 <td>64</td>
 <td>Alpha, Cray</td>
 </tr>
 <tr>
 <td>SLIP64</td>
 <td>64</td>
 <td>64</td>
 <td>64</td>
 <td>64</td>
 <td>64</td>
 <td></td>
 </tr>
 <tr>
 <td>LLP64</td>
 <td style="background-color:#ffa;">16</td>
 <td style="background-color:#afa;">32</td>
 <td style="background-color:#afa;">32</td>
 <td>64</td>
 <td>64</td>
 <td>Windows-64</td>
 </tr>
 </table>

 @subsection host-compiler-other Other compiler-specific features

 The module provides the macro ::VL_EXPORT to declare symbols exported
 from
 the library and the macro ::VL_INLINE to declare inline functions.
 Such features are not part of the C89 standard, and change
 depending on the compiler.

 @par "Example:"
 The following header file declares a function @c f that
 should be visible from outside the library.
 @code
 #include <vl/generic.h>
 VL_EXPORT void f () ;
 VL_EXPORT int i ;
 @endcode
 Notice that the macro ::VL_EXPORT needs not to be included again
 when the function is defined.

 @par "Example:"
 The following header file declares an inline function @c f:
 @code
 #include <vl/generic.h>
 VL_INLINE int f() ;

 VL_INLINE int f() { return 1 ; }
 @endcode
 Here the first instruction defines the function @c f, where the second
 declares it. Notice that since this is an inline function, its definition
 must be found in the header file rather than in an implementation file.
 Notice also that definition and declaration can be merged.

 These macros translate according to the following tables:

 <table style="font-size:70%;">
 <caption>Macros for exporting library symbols</caption>
 <tr>
 <td>Platform</td>
 <td>Macro name</td>
 <td>Value when building the library</td>
 <td>Value when importing the library</td>
 </tr>
 <tr>
 <td>Unix/GCC</td>
 <td>::VL_EXPORT</td>
 <td>empty (assumes <c>-visibility=hidden</c> GCC option)</td>
 <td><c>__attribute__((visibility ("default")))</c></td>
 </tr>
 <tr>
 <td>Win/Visual C++</td>
 <td>::VL_EXPORT</td>
 <td>@c __declspec(dllexport)</td>
 <td>@c __declspec(dllimport)</td>
 </tr>
 </table>

 <table style="font-size:70%;">
 <caption>Macros for declaring inline functions</caption>
 <tr>
 <td>Platform</td>
 <td>Macro name</td>
 <td>Value</td>
 </tr>
 <tr>
 <td>Unix/GCC</td>
 <td>::VL_INLINE</td>
 <td>static inline</td>
 </tr>
 <tr>
 <td>Win/Visual C++</td>
 <td>::VL_INLINE</td>
 <td>static __inline</td>
 </tr>
 </table>

 @section host-arch Host CPU architecture

 The module defines a symbol to identify the host CPU architecture:
 ::VL_ARCH_IX86 for Intel x86, ::VL_ARCH_IA64 for Intel 64, and so on.

 @subsection host-arch-endianness Endianness

 The module defines a symbol to identify the host CPU endianness:
 ::VL_ARCH_BIG_ENDIAN for big endian and ::VL_ARCH_LITTLE_ENDIAN for
 little endian. The functions
 ::vl_swap_host_big_endianness_8(), ::vl_swap_host_big_endianness_4(),
 ::vl_swap_host_big_endianness_2() to change the endianness
 of data (from/to host and network order).

 Recall that <em>endianness</em> concerns the way multi-byte data types
 (such as 16, 32 and 64 bits
 integers) are stored into the addressable memory.
 All CPUs uses a contiguous address range to store atomic data types
 (e.g. a 16-bit integer could
 be assigned to the addresses <c>0x10001</c> and <c>0x10002</c>), but
 the order may differ.

 - The convention is <em>big endian</em>, or in <em>network order</em>,
 if the most significant byte of the multi-byte data types is assigned to
 the smaller memory address. This is the convention used for instance
 by the PPC architecture.

 - The convention is <em>little endian</em> if  the least significant
 byte is assigned to the smaller memory address. This is the convention
 used for instance by the x86 architecture.

 @remark The names &ldquo;big endian&rdquo; and &ldquo;little endian&rdquo; are
 a little confusing. &ldquo;Big endian&rdquo; means &ldquo;big endian first&rdquo;, i.e.
 the address of the most significant byte comes first. Similarly,
 &ldquo;little endian&rdquo; means &ldquo;little endian first&rdquo;,
 in the sense that the address of the least significant byte comes first.

 Endianness is a concern when data is either exchanged with processors
 that use different conventions,
 transmitted over a network, or stored
 to a file. For the latter two cases, one usually saves data in
 big endian (network) order regardless of the host CPU.

 **/

/** @def VL_OS_LINUX
 ** @brief Defined if the host operating system is Linux.
 **/

/** @def VL_OS_MACOSX
 ** @brief Defined if the host operating system is Mac OS X.
 **/

/** @def VL_OS_WIN
 ** @brief Defined if the host operating system is Windows (32 or 64)
 **/

/** @def VL_OS_WIN64
 ** @brief Defined if the host operating system is Windows-64.
 **/

/** @def VL_COMPILER_GNUC
 ** @brief Defined if the host compiler is GNU C.
 **
 ** This macro is defined if the compiler is GNUC.
 ** Its value is calculated as
 ** @code
 ** 10000 * MAJOR + 100 * MINOR + PATCHLEVEL
 ** @endcode
 ** @see @ref host-compiler
 **/

/** @def VL_COMPILER_MSC
 ** @brief Defined if the host compiler is Microsoft Visual C++.
 ** @see @ref host-compiler
 **/

/** @def VL_COMPILER_LLP64
 ** @brief Defined if the host compiler data model is LLP64.
 ** @see @ref host-compiler-data-model
 **/

/** @def VL_COMPILER_LP64
 ** @brief Defined if the host compiler data model is LP64.
 ** @see @ref host-compiler-data-model
 **/

/** @def VL_COMPILER_ILP32
 ** @brief Defined if the host compiler data model is ILP32.
 ** @see @ref host-compiler-data-model
 **/

/** @def VL_ARCH_IX86
 ** @brief Defined if the host CPU is of the Intel x86 family.
 ** @see @ref host-arch
 **/

/** @def VL_ARCH_IA64
 ** @brief Defined if the host CPU is of the Intel Architecture-64 family.
 ** @see @ref host-arch
 **/

/** @def VL_ARCH_LITTLE_ENDIAN
 ** @brief Defined if the host CPU is little endian
 ** @see @ref host-arch-endianness
 **/

/** @def VL_ARCH_BIG_ENDIAN
 ** @brief Defined if the host CPU is big endian
 ** @see @ref host-arch-endianness
 **/

/** @def VL_INLINE
 ** @brief Adds appropriate inline function qualifier
 ** @see @ref host-compiler-others
 **/

/** @def VL_EXPORT
 ** @brief Declares a DLL exported symbol
 ** @see @ref host-compiler-others
 **/

/** --------------------------------------------------------------- */

#if defined(VL_ARCH_IX86) || defined(VL_ARCH_IA64) || defined(VL_ARCH_X64)
#define HAS_CPUID
#endif

#if defined(HAS_CPUID) & defined(VL_COMPILER_MSC)
#include <intrin.h>
VL_INLINE void
_vl_cpuid (vl_int32* info, int function)
{
  __cpuid(info, function) ;
}
#endif

#if defined(HAS_CPUID) & defined(VL_COMPILER_GNUC)
VL_INLINE void
_vl_cpuid (vl_int32* info, int function)
{
#if defined(VL_ARCH_IX86) && (defined(__PIC__) || defined(__pic__))
  /* This version is compatible with -fPIC on x386 targets. This special
   * case is required becaus
   * on such platform -fPIC alocates ebx as global offset table pointer.
   * Note that =r below will be mapped to a register different from ebx,
   * so the code is sound. */
  __asm__ __volatile__
  ("pushl %%ebx      \n" /* save %ebx */
   "cpuid            \n"
   "movl %%ebx, %1   \n" /* save what cpuid just put in %ebx */
   "popl %%ebx       \n" /* restore the old %ebx */
   : "=a"(info[0]), "=r"(info[1]), "=c"(info[2]), "=d"(info[3])
   : "a"(function)
   : "cc") ; /* clobbered (cc=condition codes) */
#else /* no -fPIC or -fPIC with a 64-bit target */
  __asm__ __volatile__
  ("cpuid"
   : "=a"(info[0]), "=b"(info[1]), "=c"(info[2]), "=d"(info[3])
   : "a"(function)
   : "cc") ;
#endif
}
#endif

#ifdef HAS_CPUID
struct x86cpu_
{
  char vendor_string [0x20] ;
  vl_bool has_sse42 ;
  vl_bool has_sse41 ;
  vl_bool has_sse3 ;
  vl_bool has_sse2 ;
  vl_bool has_sse ;
  vl_bool has_mmx ;
} x86cpu ;

vl_bool x86cpu_initialized = 0 ;

void _vl_x86cpu_init ()
{
  vl_int32 info [4] ;
  int max_func = 0 ;
  _vl_cpuid(info, 0) ;
  max_func = info[0] ;
  *((vl_int32*)x86cpu.vendor_string+0) = info[1] ;
  *((vl_int32*)x86cpu.vendor_string+1) = info[3] ;
  *((vl_int32*)x86cpu.vendor_string+2) = info[2] ;

  if (max_func >= 1) {
    _vl_cpuid(info, 1) ;
    x86cpu.has_mmx   = info[3] & (1 << 23) ;
    x86cpu.has_sse   = info[3] & (1 << 25) ;
    x86cpu.has_sse2  = info[3] & (1 << 26) ;
    x86cpu.has_sse3  = info[2] & (1 <<  0) ;
    x86cpu.has_sse41 = info[2] & (1 << 19) ;
    x86cpu.has_sse42 = info[2] & (1 << 20) ;
  }
}

VL_INLINE
struct x86cpu_ const* _vl_x86cpu_get()
{
  if (!x86cpu_initialized) _vl_x86cpu_init() ;
  return &x86cpu ;
}
#endif

/** --------------------------------------------------------------- */

vl_bool simd_enabled = 1 ;

/** @brief Enalbe/disable usage of SIMD instructions
 ** @param x set to @c true to enable SIMD instructions.
 **
 ** Notice that usage of SIMD instructions may be prevented due
 ** to lack of CPU support and data alignment issues.
 **
 ** @see ::vl_cpu_has_sse2(), ::vl_cpu_has_sse3(), etc.
 **/
void vl_set_simd_enabled (vl_bool x)
{
  simd_enabled = x ;
}

/** @brief Are SIMD instructons enabled?
 ** @return @c true is SIMD is enabled.
 **/
vl_bool vl_get_simd_enabled ()
{
  return simd_enabled ;
}

/** @brief Check for SSE3 instruction set
 ** @return @c true if SSE3 is present.
 **/
vl_bool vl_cpu_has_sse3 ()
{
#ifdef HAS_CPUID
  return _vl_x86cpu_get()->has_sse3 ;
#else
  return 0 ;
#endif
}

/** @brief Check for SSE2 instruction set
 ** @return @c true if SSE2 is present.
 **/
vl_bool vl_cpu_has_sse2 ()
{
#ifdef HAS_CPUID
  return _vl_x86cpu_get()->has_sse2 ;
#else
  return 0 ;
#endif
}

/** ------------------------------------------------------------------
 ** @brief Print host information
 **/

void vl_print_host_info ()
{
  char const *arch = 0, *endian = 0, *comp = 0, *dm = 0 ;
  int compver ;
#ifdef VL_ARCH_X64
  arch = "X64" ;
#endif
#ifdef VL_ARCH_IA64
  arch = "IA64" ;
#endif
#ifdef VL_ARCH_IX86
  arch = "IX86" ;
#endif
#ifdef VL_ARCH_PPC
  arch = "PPC" ;
#endif

#ifdef VL_ARCH_BIN_ENDIAN
  endian = "big endian" ;
#endif
#ifdef VL_ARCH_LITTLE_ENDIAN
  endian = "little endian" ;
#endif

#ifdef VL_COMPILER_MSC
  comp = "Microsoft Visual C++" ;
  compver = VL_COMPILER_MSC ;
#endif
#ifdef VL_COMPILER_GNUC
  comp = "GNU C" ;
  compver = VL_COMPILER_GNUC ;
#endif

#ifdef VL_COMPILER_LP64
  dm = "LP64" ;
#endif
#ifdef VL_COMPILER_LLP64
  dm = "LP64" ;
#endif
#ifdef VL_COMPILER_ILP32
  dm = "ILP32" ;
#endif

#define YESNO(x) ((x)?"yes":"no")

  VL_PRINTF("Host: Compiler: %s %d\n", comp, compver) ;
  VL_PRINTF("      Compiler data model: %s\n", dm) ;
  VL_PRINTF("      Compiler CPU architecture: %s\n", arch) ;
  VL_PRINTF("      Compiler CPU endianness: %s\n", endian) ;

#ifdef HAS_CPUID
  {
    struct x86cpu_ const* c = _vl_x86cpu_get() ;
    VL_PRINTF("      CPU vendor string: %s\n", c->vendor_string) ;
    VL_PRINTF("      CPU has MMX: %s\n",    YESNO(c->has_mmx)) ;
    VL_PRINTF("      CPU has SSE: %s\n",    YESNO(c->has_sse)) ;
    VL_PRINTF("      CPU has SSE2: %s\n",   YESNO(c->has_sse2)) ;
    VL_PRINTF("      CPU has SSE3: %s\n",   YESNO(c->has_sse3)) ;
    VL_PRINTF("      CPU has SSE4.1: %s\n", YESNO(c->has_sse41)) ;
    VL_PRINTF("      CPU has SSE4.2: %s\n", YESNO(c->has_sse42)) ;
    VL_PRINTF("VLFeat uses SIMD: %s\n", YESNO(vl_get_simd_enabled())) ;
  }
#endif
}