-- C490002.A -- -- Grant of Unlimited Rights -- -- Under contracts F33600-87-D-0337, F33600-84-D-0280, MDA903-79-C-0687, -- F08630-91-C-0015, and DCA100-97-D-0025, the U.S. Government obtained -- unlimited rights in the software and documentation contained herein. -- Unlimited rights are defined in DFAR 252.227-7013(a)(19). By making -- this public release, the Government intends to confer upon all -- recipients unlimited rights equal to those held by the Government. -- These rights include rights to use, duplicate, release or disclose the -- released technical data and computer software in whole or in part, in -- any manner and for any purpose whatsoever, and to have or permit others -- to do so. -- -- DISCLAIMER -- -- ALL MATERIALS OR INFORMATION HEREIN RELEASED, MADE AVAILABLE OR -- DISCLOSED ARE AS IS. THE GOVERNMENT MAKES NO EXPRESS OR IMPLIED -- WARRANTY AS TO ANY MATTER WHATSOEVER, INCLUDING THE CONDITIONS OF THE -- SOFTWARE, DOCUMENTATION OR OTHER INFORMATION RELEASED, MADE AVAILABLE -- OR DISCLOSED, OR THE OWNERSHIP, MERCHANTABILITY, OR FITNESS FOR A -- PARTICULAR PURPOSE OF SAID MATERIAL. --* -- -- OBJECTIVE: -- Check that, for a real static expression that is not part of a larger -- static expression, and whose expected type T is an ordinary fixed -- point type that is not a descendant of a formal scalar type, the value -- is rounded to the nearest integral multiple of the small of T if -- T'Machine_Rounds is true, and is truncated otherwise. Check that if -- rounding is performed, and the value is exactly halfway between two -- multiples of the small, one of the two multiples of small is used. -- -- TEST DESCRIPTION: -- The test obtains an integral multiple M1 of the small of an ordinary -- fixed point subtype S by dividing a real literal by S'Small, and then -- truncating the result using 'Truncation. It then obtains an adjacent -- multiple M2 of the small by using S'Succ (or S'Pred). It then -- constructs values which lie between these multiples: one (A) which is -- closer to M1, one (B) which is exactly halfway between M1 and M2, and -- one (C) which is closer to M2. This is done for both positive and -- negative multiples of the small. -- -- Let M1 be closer to zero than M2. Then if S'Machine_Rounds is true, -- C must be rounded to M2, A must be rounded to M1, and B must be rounded -- to either M1 or M2. If S'Machine_Rounds is false, all the values must -- be truncated to M1. -- -- A, B, and C are constructed using the following static expressions: -- -- A: constant S := M1 + (M2 - M1)/Z; -- Z slightly more than 2.0. -- B: constant S := M1 + (M2 - M1)/Z; -- Z equals 2.0. -- C: constant S := M1 + (M2 - M1)/Z; -- Z slightly less than 2.0. -- -- Since these are static expressions, they must be evaluated exactly, -- and no rounding may occur until the final result is calculated. -- -- The checks for equality between the members of (A, B, C) and (M1, M2) -- are performed at run-time within the body of a subprogram. -- -- The test performs additional checks that the rounding performed on -- real literals is consistent for ordinary fixed point subtypes. A -- named number (initialized with a literal) is assigned to a constant of -- a fixed point subtype S. The same literal is then passed to a -- subprogram, along with the constant, and an equality check is -- performed within the body of the subprogram. -- -- -- CHANGE HISTORY: -- 26 Sep 95 SAIC Initial prerelease version. -- --! package C490002_0 is type My_Fix is delta 0.0625 range -1000.0 .. 1000.0; Small : constant := My_Fix'Small; -- Named number. procedure Fixed_Subtest (A, B: in My_Fix; Msg: in String); procedure Fixed_Subtest (A, B, C: in My_Fix; Msg: in String); -- -- Positive cases: -- -- |----|-------------|-----------------|-------------------|-----------| -- | | | | | | -- 0 P_M1 Less_Pos_Than_Half Pos_Exactly_Half More_Pos_Than_Half P_M2 Positive_Real : constant := 0.11433; -- Named number. Pos_Multiplier : constant := Float'Truncation(Positive_Real/Small); -- Pos_Multiplier is the number of integral multiples of small contained -- in Positive_Real. P_M1 is thus the largest integral multiple of -- small less than or equal to Positive_Real. Note that since Positive_Real -- is a named number and not a fixed point object, P_M1 is generated -- without assuming that rounding is performed correctly for fixed point -- subtypes. Positive_Fixed : constant My_Fix := Positive_Real; P_M1 : constant My_Fix := Pos_Multiplier * Small; P_M2 : constant My_Fix := My_Fix'Succ(P_M1); -- P_M1 and P_M2 are adjacent multiples of the small of My_Fix. Note that -- 0.11433 either equals P_M1 (if it is an integral multiple of the small) -- or lies between P_M1 and P_M2 (since truncation was forced in -- generating Pos_Multiplier). It is not certain, however, exactly where -- it lies between them (halfway, less than halfway, more than halfway). -- This fact is irrelevant to the test. -- The following entities are used to verify that rounding is performed -- according to the value of 'Machine_Rounds. If language rules are -- obeyed, the intermediate expressions in the following static -- initialization expressions will not be rounded; all calculations will -- be performed exactly. The final result, however, will be rounded to -- an integral multiple of the small (either P_M1 or P_M2, depending on the -- value of My_Fix'Machine_Rounds). Thus, the value of each constant below -- will equal that of P_M1 or P_M2. Less_Pos_Than_Half : constant My_Fix := P_M1 + ((P_M2 - P_M1)/2.050); Pos_Exactly_Half : constant My_Fix := P_M1 + ((P_M2 - P_M1)/2.000); More_Pos_Than_Half : constant My_Fix := P_M1 + ((P_M2 - P_M1)/1.975); -- -- Negative cases: -- -- -|-------------|-----------------|-------------------|-----------|----| -- | | | | | | -- N_M2 More_Neg_Than_Half Neg_Exactly_Half Less_Neg_Than_Half N_M1 0 -- The descriptions for the positive cases above apply to the negative -- cases below as well. Note that, for N_M2, 'Pred is used rather than -- 'Succ. Thus, N_M2 is further from 0.0 (i.e. more negative) than N_M1. Negative_Real : constant := -467.13988; -- Named number. Neg_Multiplier : constant := Float'Truncation(Negative_Real/Small); Negative_Fixed : constant My_Fix := Negative_Real; N_M1 : constant My_Fix := Neg_Multiplier * Small; N_M2 : constant My_Fix := My_Fix'Pred(N_M1); More_Neg_Than_Half : constant My_Fix := N_M1 + ((N_M2 - N_M1)/1.980); Neg_Exactly_Half : constant My_Fix := N_M1 + ((N_M2 - N_M1)/2.000); Less_Neg_Than_Half : constant My_Fix := N_M1 + ((N_M2 - N_M1)/2.033); end C490002_0; --==================================================================-- with TCTouch; package body C490002_0 is procedure Fixed_Subtest (A, B: in My_Fix; Msg: in String) is begin TCTouch.Assert (A = B, Msg); end Fixed_Subtest; procedure Fixed_Subtest (A, B, C: in My_Fix; Msg: in String) is begin TCTouch.Assert (A = B or A = C, Msg); end Fixed_Subtest; end C490002_0; --==================================================================-- with C490002_0; -- Fixed point support. use C490002_0; with Report; procedure C490002 is begin Report.Test ("C490002", "Rounding of real static expressions: " & "ordinary fixed point subtypes"); -- Literal cases: If the named numbers used to initialize Positive_Fixed -- and Negative_Fixed are rounded to an integral multiple of the small -- prior to assignment (as expected), then Positive_Fixed and -- Negative_Fixed are already integral multiples of the small, and -- equal either P_M1 or P_M2 (resp., N_M1 or N_M2). An equality check -- can determine in which direction rounding occurred. For example: -- -- if (Positive_Fixed = P_M1) then -- Rounding was toward 0.0. -- -- Check here that the rounding direction is consistent for literals: if (Positive_Fixed = P_M1) then Fixed_Subtest (0.11433, P_M1, "Positive Fixed: literal"); else Fixed_Subtest (0.11433, P_M2, "Positive Fixed: literal"); end if; if (Negative_Fixed = N_M1) then Fixed_Subtest (-467.13988, N_M1, "Negative Fixed: literal"); else Fixed_Subtest (-467.13988, N_M2, "Negative Fixed: literal"); end if; -- Now check that rounding is performed correctly for values between -- multiples of the small, according to the value of 'Machine_Rounds: if My_Fix'Machine_Rounds then Fixed_Subtest (Pos_Exactly_Half, P_M1, P_M2, "Positive Fixed: = half"); Fixed_Subtest (More_Pos_Than_Half, P_M2, "Positive Fixed: > half"); Fixed_Subtest (Less_Pos_Than_Half, P_M1, "Positive Fixed: < half"); Fixed_Subtest (Neg_Exactly_Half, N_M1, N_M2, "Negative Fixed: = half"); Fixed_Subtest (More_Neg_Than_Half, N_M2, "Negative Fixed: > half"); Fixed_Subtest (Less_Neg_Than_Half, N_M1, "Negative Fixed: < half"); else Fixed_Subtest (Pos_Exactly_Half, P_M1, "Positive Fixed: = half"); Fixed_Subtest (More_Pos_Than_Half, P_M1, "Positive Fixed: > half"); Fixed_Subtest (Less_Pos_Than_Half, P_M1, "Positive Fixed: < half"); Fixed_Subtest (Neg_Exactly_Half, N_M1, "Negative Fixed: = half"); Fixed_Subtest (More_Neg_Than_Half, N_M1, "Negative Fixed: > half"); Fixed_Subtest (Less_Neg_Than_Half, N_M1, "Negative Fixed: < half"); end if; Report.Result; end C490002;