1. 30 Jan, 2017 1 commit
  2. 23 Jan, 2017 1 commit
    • Richard Henderson's avatar
      target-hppa: Add softfloat specializations · 005fa38d
      Richard Henderson authored
      Like the original MIPS, HPPA has the MSB of an SNaN set.
      However, it has different rules for silencing an SNaN:
      (1) msb is cleared and (2) msb-1 must be set if the fraction
      is now zero, and (implementation defined) may be set always.
      I haven't checked real hardware but chose the set always
      alternative because it's easy and within spec.
      Signed-off-by: 's avatarRichard Henderson <rth@twiddle.net>
      005fa38d
  3. 15 Aug, 2016 1 commit
  4. 24 Jun, 2016 4 commits
    • Aleksandar Markovic's avatar
      softfloat: Handle snan_bit_is_one == 0 in MIPS pickNaNMulAdd() · c27644f0
      Aleksandar Markovic authored
      Only for Mips platform, and only for cases when snan_bit_is_one is 0,
      correct the order of argument comparisons in pickNaNMulAdd().
      
      For more info, see [1], page 53, section "3.5.3 NaN Propagation".
      
      [1] "MIPS Architecture for Programmers Volume IV-j:
          The MIPS32 SIMD Architecture Module",
          Imagination Technologies LTD, Revision 1.12, February 3, 2016
      Signed-off-by: 's avatarAleksandar Markovic <aleksandar.markovic@imgtec.com>
      Reviewed-by: 's avatarLeon Alrae <leon.alrae@imgtec.com>
      Reviewed-by: 's avatarPeter Maydell <peter.maydell@linaro.org>
      [leon.alrae@imgtec.com:
       * reworded the subject of the patch
       * swapped if/else code blocks to match the commit description]
      Signed-off-by: 's avatarLeon Alrae <leon.alrae@imgtec.com>
      c27644f0
    • Aleksandar Markovic's avatar
      softfloat: For Mips only, correct default NaN values · a7c04d54
      Aleksandar Markovic authored
      Only for Mips platform, and only for cases when snan_bit_is_one is 0,
      correct default NaN values (in their 16-, 32-, and 64-bit flavors).
      
      For more info, see [1], page 84, Table 6.3 "Value Supplied When a New
      Quiet NaN Is Created", and [2], page 52, Table 3.7 "Default NaN
      Encodings".
      
      [1] "MIPS Architecture For Programmers Volume II-A:
          The MIPS64 Instruction Set Reference Manual",
          Imagination Technologies LTD, Revision 6.04, November 13, 2015
      
      [2] "MIPS Architecture for Programmers Volume IV-j:
          The MIPS32 SIMD Architecture Module",
          Imagination Technologies LTD, Revision 1.12, February 3, 2016
      Signed-off-by: 's avatarAleksandar Markovic <aleksandar.markovic@imgtec.com>
      Reviewed-by: 's avatarLeon Alrae <leon.alrae@imgtec.com>
      Reviewed-by: 's avatarPeter Maydell <peter.maydell@linaro.org>
      Signed-off-by: 's avatarLeon Alrae <leon.alrae@imgtec.com>
      a7c04d54
    • Aleksandar Markovic's avatar
      softfloat: Clean code format in fpu/softfloat-specialize.h · a59eaea6
      Aleksandar Markovic authored
      fpu/softfloat-specialize.h is the most critical file in SoftFloat
      library, since it handles numerous differences between platforms in
      relation to floating point arithmetics. This patch makes the code
      in this file more consistent format-wise, and hopefully easier to
      debug and maintain.
      Signed-off-by: 's avatarAleksandar Markovic <aleksandar.markovic@imgtec.com>
      Reviewed-by: 's avatarPeter Maydell <peter.maydell@linaro.org>
      Signed-off-by: 's avatarLeon Alrae <leon.alrae@imgtec.com>
      a59eaea6
    • Aleksandar Markovic's avatar
      softfloat: Implement run-time-configurable meaning of signaling NaN bit · af39bc8c
      Aleksandar Markovic authored
      This patch modifies SoftFloat library so that it can be configured in
      run-time in relation to the meaning of signaling NaN bit, while, at the
      same time, strictly preserving its behavior on all existing platforms.
      
      Background:
      
      In floating-point calculations, there is a need for denoting undefined or
      unrepresentable values. This is achieved by defining certain floating-point
      numerical values to be NaNs (which stands for "not a number"). For additional
      reasons, virtually all modern floating-point unit implementations use two
      kinds of NaNs: quiet and signaling. The binary representations of these two
      kinds of NaNs, as a rule, differ only in one bit (that bit is, traditionally,
      the first bit of mantissa).
      
      Up to 2008, standards for floating-point did not specify all details about
      binary representation of NaNs. More specifically, the meaning of the bit
      that is used for distinguishing between signaling and quiet NaNs was not
      strictly prescribed. (IEEE 754-2008 was the first floating-point standard
      that defined that meaning clearly, see [1], p. 35) As a result, different
      platforms took different approaches, and that presented considerable
      challenge for multi-platform emulators like QEMU.
      
      Mips platform represents the most complex case among QEMU-supported
      platforms regarding signaling NaN bit. Up to the Release 6 of Mips
      architecture, "1" in signaling NaN bit denoted signaling NaN, which is
      opposite to IEEE 754-2008 standard. From Release 6 on, Mips architecture
      adopted IEEE standard prescription, and "0" denotes signaling NaN. On top of
      that, Mips architecture for SIMD (also known as MSA, or vector instructions)
      also specifies signaling bit in accordance to IEEE standard. MSA unit can be
      implemented with both pre-Release 6 and Release 6 main processor units.
      
      QEMU uses SoftFloat library to implement various floating-point-related
      instructions on all platforms. The current QEMU implementation allows for
      defining meaning of signaling NaN bit during build time, and is implemented
      via preprocessor macro called SNAN_BIT_IS_ONE.
      
      On the other hand, the change in this patch enables SoftFloat library to be
      configured in run-time. This configuration is meant to occur during CPU
      initialization, at the moment when it is definitely known what desired
      behavior for particular CPU (or any additional FPUs) is.
      
      The change is implemented so that it is consistent with existing
      implementation of similar cases. This means that structure float_status is
      used for passing the information about desired signaling NaN bit on each
      invocation of SoftFloat functions. The additional field in float_status is
      called snan_bit_is_one, which supersedes macro SNAN_BIT_IS_ONE.
      
      IMPORTANT:
      
      This change is not meant to create any change in emulator behavior or
      functionality on any platform. It just provides the means for SoftFloat
      library to be used in a more flexible way - in other words, it will just
      prepare SoftFloat library for usage related to Mips platform and its
      specifics regarding signaling bit meaning, which is done in some of
      subsequent patches from this series.
      
      Further break down of changes:
      
        1) Added field snan_bit_is_one to the structure float_status, and
           correspondent setter function set_snan_bit_is_one().
      
        2) Constants <float16|float32|float64|floatx80|float128>_default_nan
           (used both internally and externally) converted to functions
           <float16|float32|float64|floatx80|float128>_default_nan(float_status*).
           This is necessary since they are dependent on signaling bit meaning.
           At the same time, for the sake of code cleanup and simplicity, constants
           <floatx80|float128>_default_nan_<low|high> (used only internally within
           SoftFloat library) are removed, as not needed.
      
        3) Added a float_status* argument to SoftFloat library functions
           XXX_is_quiet_nan(XXX a_), XXX_is_signaling_nan(XXX a_),
           XXX_maybe_silence_nan(XXX a_). This argument must be present in
           order to enable correct invocation of new version of functions
           XXX_default_nan(). (XXX is <float16|float32|float64|floatx80|float128>
           here)
      
        4) Updated code for all platforms to reflect changes in SoftFloat library.
           This change is twofolds: it includes modifications of SoftFloat library
           functions invocations, and an addition of invocation of function
           set_snan_bit_is_one() during CPU initialization, with arguments that
           are appropriate for each particular platform. It was established that
           all platforms zero their main CPU data structures, so snan_bit_is_one(0)
           in appropriate places is not added, as it is not needed.
      
      [1] "IEEE Standard for Floating-Point Arithmetic",
          IEEE Computer Society, August 29, 2008.
      Signed-off-by: 's avatarThomas Schwinge <thomas@codesourcery.com>
      Signed-off-by: 's avatarMaciej W. Rozycki <macro@codesourcery.com>
      Signed-off-by: 's avatarAleksandar Markovic <aleksandar.markovic@imgtec.com>
      Tested-by: 's avatarBastian Koppelmann <kbastian@mail.uni-paderborn.de>
      Reviewed-by: 's avatarLeon Alrae <leon.alrae@imgtec.com>
      Tested-by: 's avatarLeon Alrae <leon.alrae@imgtec.com>
      Reviewed-by: 's avatarPeter Maydell <peter.maydell@linaro.org>
      [leon.alrae@imgtec.com:
       * cherry-picked 2 chunks from patch #2 to fix compilation warnings]
      Signed-off-by: 's avatarLeon Alrae <leon.alrae@imgtec.com>
      af39bc8c
  5. 23 Mar, 2016 1 commit
  6. 22 Jan, 2016 1 commit
  7. 04 Jun, 2015 1 commit
  8. 06 Feb, 2015 3 commits
  9. 29 Jan, 2015 3 commits
  10. 31 Oct, 2012 1 commit
  11. 22 Sep, 2012 2 commits
  12. 17 Mar, 2012 1 commit
  13. 19 Oct, 2011 1 commit
  14. 29 Jul, 2011 1 commit
  15. 03 Jun, 2011 1 commit
  16. 25 Apr, 2011 1 commit
    • Aurelien Jarno's avatar
      softfloat: fix floatx80 handling of NaN · e2f42204
      Aurelien Jarno authored
      The floatx80 format uses an explicit bit that should be taken into account
      when converting to and from commonNaN format.
      
      When converting to commonNaN, the explicit bit should be removed if it is
      a 1, and a default NaN should be used if it is 0.
      
      When converting from commonNan, the explicit bit should be added.
      Signed-off-by: 's avatarAurelien Jarno <aurelien@aurel32.net>
      e2f42204
  17. 12 Apr, 2011 1 commit
  18. 21 Mar, 2011 2 commits
  19. 24 Feb, 2011 1 commit
  20. 10 Feb, 2011 4 commits
  21. 20 Jan, 2011 1 commit
    • Aurelien Jarno's avatar
      softfloat: fix floatx80_is_{quiet,signaling}_nan() · de4af5f7
      Aurelien Jarno authored
      floatx80_is_{quiet,signaling}_nan() functions are incorrectly detecting
      the type of NaN, depending on SNAN_BIT_IS_ONE, one of the two is
      returning the correct value, and the other true for any kind of NaN.
      
      This patch fixes that by applying the same kind of comparison as for
      other float formats, but taking into account the explicit bit.
      Signed-off-by: 's avatarAurelien Jarno <aurelien@aurel32.net>
      de4af5f7
  22. 14 Jan, 2011 2 commits
  23. 06 Jan, 2011 5 commits