From: Eric Botcazou Date: Mon, 23 Nov 2020 10:39:05 +0000 (+0100) Subject: [Ada] Small adjustments to fixed-point I/O units X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=951d7d1319923e5188df3224a9f79ee5804bac80;p=gcc.git [Ada] Small adjustments to fixed-point I/O units gcc/ada/ * libgnat/a-tifiio.adb: Adjust documentation. (OK_Get_32): Compare the object size of the base type. (OK_Put_32): Likewise. (OK_Get_64): Likewise. (OK_Put_64): Likewise. * libgnat/a-tifiio__128.adb: Adjust documentation. (OK_Get_32): Compare the object size of the base type. (OK_Put_32): Likewise. (OK_Get_64): Likewise. (OK_Put_64): Likewise. (OK_Get_128): Likewise. (OK_Put_128): Likewise. * libgnat/a-wtfiio.adb (OK_Get_32): Likewise. (OK_Put_32): Likewise. (OK_Get_64): Likewise. (OK_Put_64): Likewise * libgnat/a-wtfiio__128.adb (OK_Get_32): Likewise. (OK_Put_32): Likewise. (OK_Get_64): Likewise. (OK_Put_64): Likewise. (OK_Get_128): Likewise. (OK_Put_128): Likewise. * libgnat/a-ztfiio.adb (OK_Get_32): Likewise. (OK_Put_32): Likewise. (OK_Get_64): Likewise. (OK_Put_64): Likewise * libgnat/a-ztfiio__128.adb (OK_Get_32): Likewise. (OK_Put_32): Likewise. (OK_Get_64): Likewise. (OK_Put_64): Likewise. (OK_Get_128): Likewise. (OK_Put_128): Likewise. --- diff --git a/gcc/ada/libgnat/a-tifiio.adb b/gcc/ada/libgnat/a-tifiio.adb index b7d9471873b..61c68ec8ba7 100644 --- a/gcc/ada/libgnat/a-tifiio.adb +++ b/gcc/ada/libgnat/a-tifiio.adb @@ -29,8 +29,9 @@ -- -- ------------------------------------------------------------------------------ --- Fixed point I/O --- --------------- +-- ------------------- +-- - Fixed point I/O - +-- ------------------- -- The following text documents implementation details of the fixed point -- input/output routines in the GNAT runtime. The first part describes the @@ -40,7 +41,7 @@ -- Subsequently these are reduced to implementation constraints and the impact -- of these constraints on a few possible approaches to input/output is given. -- Based on this analysis, a specific implementation is selected for use in --- the GNAT runtime. Finally, the chosen algorithm is analyzed numerically in +-- the GNAT runtime. Finally the chosen algorithms are analyzed numerically in -- order to provide user-level documentation on limits for range and precision -- of fixed point types as well as accuracy of input/output conversions. @@ -68,7 +69,7 @@ -- Operations -- ---------- --- 'Image and 'Wide_Image (see RM 3.5(34)) +-- [Wide_[Wide_]]Image attribute (see RM 3.5(27.1/2)) -- These attributes return a decimal real literal best approximating -- the value (rounded away from zero if halfway between) with a @@ -88,7 +89,7 @@ -- attributes, although it would be nice to be able to output more -- than S'Aft digits after the decimal point for values of subtype S. --- 'Value and 'Wide_Value attribute (RM 3.5(40-55)) +-- [Wide_[Wide_]]Value attribute (RM 3.5(39.1/2)) -- Since the input can be given in any base in the range 2..16, -- accurate conversion to a fixed point number may require @@ -121,7 +122,7 @@ -- be less than 2.0**(-53). -- In GNAT, Fine_Delta is 2.0**(-63), and Duration for example is a 64-bit --- type. This means that a floating-point type with 63 bits of mantissa needs +-- type. This means that a floating-point type with 64 bits of mantissa needs -- to be used, which is only generally available on the x86 architecture. It -- would still be possible to use multi-precision floating point to perform -- calculations using longer mantissas, but this is a much harder approach. @@ -137,9 +138,21 @@ -- Fixed-precision integer arithmetic has the advantage of simplicity and -- speed. For the most common fixed point types this would be a perfect --- solution. The downside however may be a too limited set of acceptable +-- solution. The downside however may be a restricted set of acceptable -- fixed point types. +-- Implementation Choices +-- ---------------------- + +-- The current implementation in the GNAT runtime uses fixed-precision integer +-- arithmetic for fixed point types whose Small is the ratio of two integers +-- whose magnitude is bounded relatively to the size of the mantissa, with a +-- two-tiered approach for 32-bit and 64-bit fixed point types. For the other +-- fixed point types, the implementation uses floating-point arithmetic. + +-- The exact requirements of the algorithms are analyzed and documented along +-- with the implementation in their respective units. + with Interfaces; with Ada.Text_IO.Fixed_Aux; with Ada.Text_IO.Float_Aux; @@ -171,7 +184,7 @@ package body Ada.Text_IO.Fixed_IO is -- static (although it is not a static expressions in the RM sense). OK_Get_32 : constant Boolean := - Num'Object_Size <= 32 + Num'Base'Object_Size <= 32 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**31) or else @@ -182,7 +195,7 @@ package body Ada.Text_IO.Fixed_IO is -- These conditions are derived from the prerequisites of System.Value_F OK_Put_32 : constant Boolean := - Num'Object_Size <= 32 + Num'Base'Object_Size <= 32 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**31) or else @@ -196,7 +209,7 @@ package body Ada.Text_IO.Fixed_IO is -- These conditions are derived from the prerequisites of System.Image_F OK_Get_64 : constant Boolean := - Num'Object_Size <= 64 + Num'Base'Object_Size <= 64 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**63) or else @@ -207,7 +220,7 @@ package body Ada.Text_IO.Fixed_IO is -- These conditions are derived from the prerequisites of System.Value_F OK_Put_64 : constant Boolean := - Num'Object_Size <= 64 + Num'Base'Object_Size <= 64 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**63) or else diff --git a/gcc/ada/libgnat/a-tifiio__128.adb b/gcc/ada/libgnat/a-tifiio__128.adb index 4dea63ce83b..578beb1fb1c 100644 --- a/gcc/ada/libgnat/a-tifiio__128.adb +++ b/gcc/ada/libgnat/a-tifiio__128.adb @@ -29,8 +29,9 @@ -- -- ------------------------------------------------------------------------------ --- Fixed point I/O --- --------------- +-- ------------------- +-- - Fixed point I/O - +-- ------------------- -- The following text documents implementation details of the fixed point -- input/output routines in the GNAT runtime. The first part describes the @@ -40,7 +41,7 @@ -- Subsequently these are reduced to implementation constraints and the impact -- of these constraints on a few possible approaches to input/output is given. -- Based on this analysis, a specific implementation is selected for use in --- the GNAT runtime. Finally, the chosen algorithm is analyzed numerically in +-- the GNAT runtime. Finally the chosen algorithms are analyzed numerically in -- order to provide user-level documentation on limits for range and precision -- of fixed point types as well as accuracy of input/output conversions. @@ -68,7 +69,7 @@ -- Operations -- ---------- --- 'Image and 'Wide_Image (see RM 3.5(34)) +-- [Wide_[Wide_]]Image attribute (see RM 3.5(27.1/2)) -- These attributes return a decimal real literal best approximating -- the value (rounded away from zero if halfway between) with a @@ -88,7 +89,7 @@ -- attributes, although it would be nice to be able to output more -- than S'Aft digits after the decimal point for values of subtype S. --- 'Value and 'Wide_Value attribute (RM 3.5(40-55)) +-- [Wide_[Wide_]]Value attribute (RM 3.5(39.1/2)) -- Since the input can be given in any base in the range 2..16, -- accurate conversion to a fixed point number may require @@ -120,9 +121,9 @@ -- available has 53 bits of mantissa. This means that Fine_Delta cannot -- be less than 2.0**(-53). --- In GNAT, Fine_Delta is 2.0**(-63), and Duration for example is a 64-bit --- type. This means that a floating-point type with 63 bits of mantissa needs --- to be used, which is only generally available on the x86 architecture. It +-- In GNAT, Fine_Delta is 2.0**(-127), and Duration for example is a 64-bit +-- type. This means that a floating-point type with 128 bits of mantissa needs +-- to be used, which currently does not exist in any common architecture. It -- would still be possible to use multi-precision floating point to perform -- calculations using longer mantissas, but this is a much harder approach. @@ -137,9 +138,21 @@ -- Fixed-precision integer arithmetic has the advantage of simplicity and -- speed. For the most common fixed point types this would be a perfect --- solution. The downside however may be a too limited set of acceptable +-- solution. The downside however may be a restricted set of acceptable -- fixed point types. +-- Implementation Choices +-- ---------------------- + +-- The current implementation in the GNAT runtime uses fixed-precision integer +-- arithmetic for fixed point types whose Small is the ratio of two integers +-- whose magnitude is bounded relatively to the size of the mantissa, with a +-- three-tiered approach for 32-bit, 64-bit and 128-bit fixed point types. For +-- other fixed point types, the implementation uses floating-point arithmetic. + +-- The exact requirements of the algorithms are analyzed and documented along +-- with the implementation in their respective units. + with Interfaces; with Ada.Text_IO.Fixed_Aux; with Ada.Text_IO.Float_Aux; @@ -178,7 +191,7 @@ package body Ada.Text_IO.Fixed_IO is -- in the RM sense). OK_Get_32 : constant Boolean := - Num'Object_Size <= 32 + Num'Base'Object_Size <= 32 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**31) or else @@ -189,7 +202,7 @@ package body Ada.Text_IO.Fixed_IO is -- These conditions are derived from the prerequisites of System.Value_F OK_Put_32 : constant Boolean := - Num'Object_Size <= 32 + Num'Base'Object_Size <= 32 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**31) or else @@ -203,7 +216,7 @@ package body Ada.Text_IO.Fixed_IO is -- These conditions are derived from the prerequisites of System.Image_F OK_Get_64 : constant Boolean := - Num'Object_Size <= 64 + Num'Base'Object_Size <= 64 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**63) or else @@ -214,7 +227,7 @@ package body Ada.Text_IO.Fixed_IO is -- These conditions are derived from the prerequisites of System.Value_F OK_Put_64 : constant Boolean := - Num'Object_Size <= 64 + Num'Base'Object_Size <= 64 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**63) or else @@ -228,7 +241,7 @@ package body Ada.Text_IO.Fixed_IO is -- These conditions are derived from the prerequisites of System.Image_F OK_Get_128 : constant Boolean := - Num'Object_Size <= 128 + Num'Base'Object_Size <= 128 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**127) or else @@ -239,7 +252,7 @@ package body Ada.Text_IO.Fixed_IO is -- These conditions are derived from the prerequisites of System.Value_F OK_Put_128 : constant Boolean := - Num'Object_Size <= 128 + Num'Base'Object_Size <= 128 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**127) or else diff --git a/gcc/ada/libgnat/a-wtfiio.adb b/gcc/ada/libgnat/a-wtfiio.adb index fa9c1e08c08..570c5da72d8 100644 --- a/gcc/ada/libgnat/a-wtfiio.adb +++ b/gcc/ada/libgnat/a-wtfiio.adb @@ -62,7 +62,7 @@ package body Ada.Wide_Text_IO.Fixed_IO is -- static (although it is not a static expressions in the RM sense). OK_Get_32 : constant Boolean := - Num'Object_Size <= 32 + Num'Base'Object_Size <= 32 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**31) or else @@ -73,7 +73,7 @@ package body Ada.Wide_Text_IO.Fixed_IO is -- These conditions are derived from the prerequisites of System.Value_F OK_Put_32 : constant Boolean := - Num'Object_Size <= 32 + Num'Base'Object_Size <= 32 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**31) or else @@ -87,7 +87,7 @@ package body Ada.Wide_Text_IO.Fixed_IO is -- These conditions are derived from the prerequisites of System.Image_F OK_Get_64 : constant Boolean := - Num'Object_Size <= 64 + Num'Base'Object_Size <= 64 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**63) or else @@ -98,7 +98,7 @@ package body Ada.Wide_Text_IO.Fixed_IO is -- These conditions are derived from the prerequisites of System.Value_F OK_Put_64 : constant Boolean := - Num'Object_Size <= 64 + Num'Base'Object_Size <= 64 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**63) or else diff --git a/gcc/ada/libgnat/a-wtfiio__128.adb b/gcc/ada/libgnat/a-wtfiio__128.adb index 846c036dd03..aa45e5d375d 100644 --- a/gcc/ada/libgnat/a-wtfiio__128.adb +++ b/gcc/ada/libgnat/a-wtfiio__128.adb @@ -69,7 +69,7 @@ package body Ada.Wide_Text_IO.Fixed_IO is -- in the RM sense). OK_Get_32 : constant Boolean := - Num'Object_Size <= 32 + Num'Base'Object_Size <= 32 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**31) or else @@ -80,7 +80,7 @@ package body Ada.Wide_Text_IO.Fixed_IO is -- These conditions are derived from the prerequisites of System.Value_F OK_Put_32 : constant Boolean := - Num'Object_Size <= 32 + Num'Base'Object_Size <= 32 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**31) or else @@ -94,7 +94,7 @@ package body Ada.Wide_Text_IO.Fixed_IO is -- These conditions are derived from the prerequisites of System.Image_F OK_Get_64 : constant Boolean := - Num'Object_Size <= 64 + Num'Base'Object_Size <= 64 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**63) or else @@ -105,7 +105,7 @@ package body Ada.Wide_Text_IO.Fixed_IO is -- These conditions are derived from the prerequisites of System.Value_F OK_Put_64 : constant Boolean := - Num'Object_Size <= 64 + Num'Base'Object_Size <= 64 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**63) or else @@ -119,7 +119,7 @@ package body Ada.Wide_Text_IO.Fixed_IO is -- These conditions are derived from the prerequisites of System.Image_F OK_Get_128 : constant Boolean := - Num'Object_Size <= 128 + Num'Base'Object_Size <= 128 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**127) or else @@ -130,7 +130,7 @@ package body Ada.Wide_Text_IO.Fixed_IO is -- These conditions are derived from the prerequisites of System.Value_F OK_Put_128 : constant Boolean := - Num'Object_Size <= 128 + Num'Base'Object_Size <= 128 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**127) or else diff --git a/gcc/ada/libgnat/a-ztfiio.adb b/gcc/ada/libgnat/a-ztfiio.adb index 57b258e0af5..3c3224d3c57 100644 --- a/gcc/ada/libgnat/a-ztfiio.adb +++ b/gcc/ada/libgnat/a-ztfiio.adb @@ -62,7 +62,7 @@ package body Ada.Wide_Wide_Text_IO.Fixed_IO is -- static (although it is not a static expressions in the RM sense). OK_Get_32 : constant Boolean := - Num'Object_Size <= 32 + Num'Base'Object_Size <= 32 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**31) or else @@ -73,7 +73,7 @@ package body Ada.Wide_Wide_Text_IO.Fixed_IO is -- These conditions are derived from the prerequisites of System.Value_F OK_Put_32 : constant Boolean := - Num'Object_Size <= 32 + Num'Base'Object_Size <= 32 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**31) or else @@ -87,7 +87,7 @@ package body Ada.Wide_Wide_Text_IO.Fixed_IO is -- These conditions are derived from the prerequisites of System.Image_F OK_Get_64 : constant Boolean := - Num'Object_Size <= 64 + Num'Base'Object_Size <= 64 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**63) or else @@ -98,7 +98,7 @@ package body Ada.Wide_Wide_Text_IO.Fixed_IO is -- These conditions are derived from the prerequisites of System.Value_F OK_Put_64 : constant Boolean := - Num'Object_Size <= 64 + Num'Base'Object_Size <= 64 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**63) or else diff --git a/gcc/ada/libgnat/a-ztfiio__128.adb b/gcc/ada/libgnat/a-ztfiio__128.adb index fcb7077d1ef..3254fb8c7de 100644 --- a/gcc/ada/libgnat/a-ztfiio__128.adb +++ b/gcc/ada/libgnat/a-ztfiio__128.adb @@ -70,7 +70,7 @@ package body Ada.Wide_Wide_Text_IO.Fixed_IO is -- in the RM sense). OK_Get_32 : constant Boolean := - Num'Object_Size <= 32 + Num'Base'Object_Size <= 32 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**31) or else @@ -81,7 +81,7 @@ package body Ada.Wide_Wide_Text_IO.Fixed_IO is -- These conditions are derived from the prerequisites of System.Value_F OK_Put_32 : constant Boolean := - Num'Object_Size <= 32 + Num'Base'Object_Size <= 32 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**31) or else @@ -95,7 +95,7 @@ package body Ada.Wide_Wide_Text_IO.Fixed_IO is -- These conditions are derived from the prerequisites of System.Image_F OK_Get_64 : constant Boolean := - Num'Object_Size <= 64 + Num'Base'Object_Size <= 64 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**63) or else @@ -106,7 +106,7 @@ package body Ada.Wide_Wide_Text_IO.Fixed_IO is -- These conditions are derived from the prerequisites of System.Value_F OK_Put_64 : constant Boolean := - Num'Object_Size <= 64 + Num'Base'Object_Size <= 64 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**63) or else @@ -120,7 +120,7 @@ package body Ada.Wide_Wide_Text_IO.Fixed_IO is -- These conditions are derived from the prerequisites of System.Image_F OK_Get_128 : constant Boolean := - Num'Object_Size <= 128 + Num'Base'Object_Size <= 128 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**127) or else @@ -131,7 +131,7 @@ package body Ada.Wide_Wide_Text_IO.Fixed_IO is -- These conditions are derived from the prerequisites of System.Value_F OK_Put_128 : constant Boolean := - Num'Object_Size <= 128 + Num'Base'Object_Size <= 128 and then ((Num'Small_Numerator = 1 and then Num'Small_Denominator <= 2**127) or else