diff options
Diffstat (limited to 'gcc/ada/g-mbdira.adb')
| -rw-r--r-- | gcc/ada/g-mbdira.adb | 42 |
1 files changed, 12 insertions, 30 deletions
diff --git a/gcc/ada/g-mbdira.adb b/gcc/ada/g-mbdira.adb index e7e1c470d67..f5fd4dce60d 100644 --- a/gcc/ada/g-mbdira.adb +++ b/gcc/ada/g-mbdira.adb @@ -35,25 +35,8 @@ with Interfaces; use Interfaces; package body GNAT.MBBS_Discrete_Random is - ------------------------- - -- Implementation Note -- - ------------------------- - - -- The design of this spec is a bit awkward, as a result of Ada 95 not - -- permitting in-out parameters for function formals (most naturally - -- Generator values would be passed this way). In pure Ada 95, the only - -- solution would be to add a self-referential component to the generator - -- allowing access to the generator object from inside the function. This - -- would work because the generator is limited, which prevents any copy. - - -- This is a bit heavy, so what we do is to use Unrestricted_Access to - -- get a pointer to the state in the passed Generator. This works because - -- Generator is a limited type and will thus always be passed by reference. - package Calendar renames Ada.Calendar; - type Pointer is access all State; - Fits_In_32_Bits : constant Boolean := Rst'Size < 31 or else (Rst'Size = 31 @@ -109,7 +92,7 @@ package body GNAT.MBBS_Discrete_Random is ------------ function Random (Gen : Generator) return Rst is - Genp : constant Pointer := Gen.Gen_State'Unrestricted_Access; + S : State renames Gen.Writable.Self.Gen_State; Temp : Int; TF : Flt; @@ -124,21 +107,21 @@ package body GNAT.MBBS_Discrete_Random is -- Continue with computation if non-flat range - Genp.X1 := Square_Mod_N (Genp.X1, Genp.P); - Genp.X2 := Square_Mod_N (Genp.X2, Genp.Q); - Temp := Genp.X2 - Genp.X1; + S.X1 := Square_Mod_N (S.X1, S.P); + S.X2 := Square_Mod_N (S.X2, S.Q); + Temp := S.X2 - S.X1; -- Following duplication is not an error, it is a loop unwinding! if Temp < 0 then - Temp := Temp + Genp.Q; + Temp := Temp + S.Q; end if; if Temp < 0 then - Temp := Temp + Genp.Q; + Temp := Temp + S.Q; end if; - TF := Offs + (Flt (Temp) * Flt (Genp.P) + Flt (Genp.X1)) * Genp.Scl; + TF := Offs + (Flt (Temp) * Flt (S.P) + Flt (S.X1)) * S.Scl; -- Pathological, but there do exist cases where the rounding implicit -- in calculating the scale factor will cause rounding to 'Last + 1. @@ -160,7 +143,7 @@ package body GNAT.MBBS_Discrete_Random is ----------- procedure Reset (Gen : Generator; Initiator : Integer) is - Genp : constant Pointer := Gen.Gen_State'Unrestricted_Access; + S : State renames Gen.Writable.Self.Gen_State; X1, X2 : Int; begin @@ -174,7 +157,7 @@ package body GNAT.MBBS_Discrete_Random is -- Eliminate effects of small Initiators - Genp.all := + S := (X1 => X1, X2 => X2, P => K1, @@ -188,7 +171,7 @@ package body GNAT.MBBS_Discrete_Random is ----------- procedure Reset (Gen : Generator) is - Genp : constant Pointer := Gen.Gen_State'Unrestricted_Access; + S : State renames Gen.Writable.Self.Gen_State; Now : constant Calendar.Time := Calendar.Clock; X1 : Int; X2 : Int; @@ -210,7 +193,7 @@ package body GNAT.MBBS_Discrete_Random is X2 := Square_Mod_N (X2, K2); end loop; - Genp.all := + S := (X1 => X1, X2 => X2, P => K1, @@ -225,9 +208,8 @@ package body GNAT.MBBS_Discrete_Random is ----------- procedure Reset (Gen : Generator; From_State : State) is - Genp : constant Pointer := Gen.Gen_State'Unrestricted_Access; begin - Genp.all := From_State; + Gen.Writable.Self.Gen_State := From_State; end Reset; ---------- |