DPF

DISTRHO Plugin Framework
Log | Files | Refs | Submodules | README | LICENSE

ScopedDenormalDisable.hpp (3694B)

      1 /*
      2  * DISTRHO Plugin Framework (DPF)
      3  * Copyright (C) 2012-2023 Filipe Coelho <falktx@falktx.com>
      4  *
      5  * Permission to use, copy, modify, and/or distribute this software for any purpose with
      6  * or without fee is hereby granted, provided that the above copyright notice and this
      7  * permission notice appear in all copies.
      8  *
      9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD
     10  * TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN
     11  * NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
     12  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
     13  * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
     14  * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
     15  */
     16 
     17 #ifndef DISTRHO_SCOPED_DENORMAL_DISABLE_HPP_INCLUDED
     18 #define DISTRHO_SCOPED_DENORMAL_DISABLE_HPP_INCLUDED
     19 
     20 #include "../DistrhoUtils.hpp"
     21 
     22 #ifdef __SSE2_MATH__
     23 # include <xmmintrin.h>
     24 #endif
     25 
     26 START_NAMESPACE_DISTRHO
     27 
     28 // --------------------------------------------------------------------------------------------------------------------
     29 // ScopedDenormalDisable class definition
     30 
     31 /**
     32    ScopedDenormalDisable is a handy class for disabling denormal numbers during a function scope.
     33    Denormal numbers can happen in IIR or other types of filters, they are often very slow.
     34 
     35    Use this class with care! Messing up with the global state is bound to make some hosts unhappy.
     36  */
     37 class ScopedDenormalDisable {
     38 public:
     39     /*
     40      * Constructor.
     41      * Current cpu flags will saved, then denormals-as-zero and flush-to-zero set on top.
     42      */
     43     inline ScopedDenormalDisable() noexcept;
     44 
     45     /*
     46      * Destructor.
     47      * CPU flags will be restored to the value obtained in the constructor.
     48      */
     49     inline ~ScopedDenormalDisable() noexcept
     50     {
     51         setFlags(oldflags);
     52     }
     53 
     54 private:
     55    #if defined(__SSE2_MATH__)
     56     typedef uint cpuflags_t;
     57    #elif defined(__aarch64__)
     58     typedef uint64_t cpuflags_t;
     59    #elif defined(__arm__) && !defined(__SOFTFP__)
     60     typedef uint32_t cpuflags_t;
     61    #else
     62     typedef char cpuflags_t;
     63    #endif
     64 
     65     // retrieved on constructor, reset to it on destructor
     66     cpuflags_t oldflags;
     67 
     68     // helper function to set cpu flags
     69     inline void setFlags(cpuflags_t flags) noexcept;
     70 
     71     DISTRHO_DECLARE_NON_COPYABLE(ScopedDenormalDisable)
     72     DISTRHO_PREVENT_HEAP_ALLOCATION
     73 };
     74 
     75 // --------------------------------------------------------------------------------------------------------------------
     76 // ScopedDenormalDisable class implementation
     77 
     78 inline ScopedDenormalDisable::ScopedDenormalDisable() noexcept
     79     : oldflags(0)
     80 {
     81    #if defined(__SSE2_MATH__)
     82     oldflags = _mm_getcsr();
     83     setFlags(oldflags | 0x8040);
     84    #elif defined(__aarch64__)
     85     __asm__ __volatile__("mrs %0, fpcr" : "=r" (oldflags));
     86     setFlags(oldflags | 0x1000000);
     87     __asm__ __volatile__("isb");
     88    #elif defined(__arm__) && !defined(__SOFTFP__)
     89     __asm__ __volatile__("vmrs %0, fpscr" : "=r" (oldflags));
     90     setFlags(oldflags | 0x1000000);
     91    #endif
     92 }
     93 
     94 inline void ScopedDenormalDisable::setFlags(const cpuflags_t flags) noexcept
     95 {
     96    #if defined(__SSE2_MATH__)
     97     _mm_setcsr(flags);
     98    #elif defined(__aarch64__)
     99     __asm__ __volatile__("msr fpcr, %0" :: "r" (flags));
    100    #elif defined(__arm__) && !defined(__SOFTFP__)
    101     __asm__ __volatile__("vmsr fpscr, %0" :: "r" (flags));
    102    #else
    103     // unused
    104     (void)flags;
    105    #endif
    106 }
    107 
    108 // --------------------------------------------------------------------------------------------------------------------
    109 
    110 END_NAMESPACE_DISTRHO
    111 
    112 #endif // DISTRHO_SCOPED_DENORMAL_DISABLE_HPP_INCLUDED