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damakidamaki
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Merge pull request #4 from damaki/topic/add-reflection-tests
Add tests for reflected & normal tables produce equivalent CRCs
2 parents b354514 + 8c627f0 commit 970dc56

5 files changed

Lines changed: 183 additions & 10 deletions

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‎src/libcrc-generic_nbit_crcs-bitwise.adb‎

Lines changed: 3 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -100,13 +100,11 @@ is
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Reason =>
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"Statement has effect for different generic instantiations");
102102

103-
if Reflect_Output then
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if not Reflected_Polynomial then
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if Reflect_Output /= Reflected_Polynomial then
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106-
pragma Warnings (GNATprove, On, "statement has no effect");
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pragma Warnings (GNATprove, On, "statement has no effect");
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108-
CRC := Bit_Reverse_CRC (CRC);
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end if;
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CRC := Bit_Reverse_CRC (CRC);
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end if;
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return CRC xor Final_XOR;

‎src/libcrc-generic_nbit_crcs-table_based.adb‎

Lines changed: 3 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -97,13 +97,11 @@ package body LibCRC.Generic_Nbit_CRCs.Table_Based with SPARK_Mode is
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Reason =>
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"Statement has effect for different generic instantiations");
9999

100-
if Reflect_Output then
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if not CRC_Table_Reflected then
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if Reflect_Output /= CRC_Table_Reflected then
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103-
pragma Warnings (GNATprove, On, "statement has no effect");
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pragma Warnings (GNATprove, On, "statement has no effect");
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105-
CRC := Bit_Reverse_CRC (CRC);
106-
end if;
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CRC := Bit_Reverse_CRC (CRC);
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end if;
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109107
return CRC xor Final_XOR;

‎tests/unit_tests/src/crc_table_test_suites.adb‎

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Original file line numberDiff line numberDiff line change
@@ -15,6 +15,7 @@ with LibCRC.Predefined_Constant_Tables;
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with LibCRC.Predefined_Elaborated_Tables;
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with Generic_CRC_Table_Tests;
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with Reflection_Tests;
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package body CRC_Table_Test_Suites
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is
@@ -393,6 +394,8 @@ is
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Table_64_Poly_259C84CBA6426349_Tests.Add_To_Suite (S.all);
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Table_64_Poly_AD93D23594C93659_Tests.Add_To_Suite (S.all);
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Reflection_Tests.Add_To_Suite (S.all);
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return S;
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end Suite;
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‎tests/unit_tests/src/reflection_tests.adb‎

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,148 @@
1+
--
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-- Copyright 2025 (C) Daniel King
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--
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-- SPDX-License-Identifier: Apache-2.0
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--
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with Interfaces; use Interfaces;
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with AUnit.Assertions; use AUnit.Assertions;
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with LibCRC;
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with LibCRC.CRC_32bit;
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with LibCRC.Generic_Nbit_CRCs.Table_Based;
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with LibCRC.Generic_Nbit_CRCs.Bitwise;
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package body Reflection_Tests is
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-- Use the CRC-32 polynomial for testing
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Test_Polynomial : constant Unsigned_32 := 16#04C11DB7#;
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-- Other parameters for testing
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Test_Seed : constant Unsigned_32 := 16#12345678#;
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Test_Final_XOR : constant Unsigned_32 := 16#87654321#;
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Test_Table : aliased constant LibCRC.CRC_32bit.CRC_Table_Type :=
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LibCRC.CRC_32bit.Generate_Table (Test_Polynomial);
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Test_Table_Reflected :
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aliased constant LibCRC.CRC_32bit.CRC_Table_Type :=
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LibCRC.CRC_32bit.Generate_Table_Reflected
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(LibCRC.CRC_32bit.Bit_Reverse_CRC (Test_Polynomial));
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---------------------------
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-- Test_Table_Reflection --
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---------------------------
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-- Test that equivalent CRCs are output for two table-based CRCs that
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-- are identical, except one uses a reflected table and the other a
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-- normal (non-reflected) table.
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--
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-- The test is performed for all possible combinations of Reflect_Input
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-- and Reflect_Output.
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procedure Test_Table_Reflection (T : in out Test_Fixture) is
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Test_Data : constant LibCRC.Byte_Array := (1, 2, 3, 4, 5, 255, 254, 253);
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begin
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for Reflect_Input in Boolean'Range loop
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for Reflect_Output in Boolean'Range loop
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declare
49+
package Test_CRC is new LibCRC.CRC_32bit.Table_Based
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(Seed => Test_Seed,
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Final_XOR => Test_Final_XOR,
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Reflect_Input => Reflect_Input,
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Reflect_Output => Reflect_Output,
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CRC_Table_Reflected => False,
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CRC_Table => Test_Table'Access);
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package Test_CRC_Reflected is new LibCRC.CRC_32bit.Table_Based
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(Seed => Test_Seed,
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Final_XOR => Test_Final_XOR,
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Reflect_Input => Reflect_Input,
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Reflect_Output => Reflect_Output,
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CRC_Table_Reflected => True,
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CRC_Table => Test_Table_Reflected'Access);
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65+
CRC_1 : Unsigned_32;
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CRC_2 : Unsigned_32;
67+
begin
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69+
CRC_1 := Test_CRC.Calculate (Test_Data);
70+
CRC_2 := Test_CRC_Reflected.Calculate (Test_Data);
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Assert (CRC_1 = CRC_2,
73+
"CRC mismatch for Reflect_Input = "
74+
& Reflect_Input'Image & ", Reflect_Output = "
75+
& Reflect_Output'Image & ":"
76+
& CRC_1'Image & " !="
77+
& CRC_2'Image);
78+
end;
79+
end loop;
80+
end loop;
81+
end Test_Table_Reflection;
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83+
-----------------------------
84+
-- Test_Bitwise_Reflection --
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-----------------------------
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-- Test that equivalent CRCs are output for two bitwise CRCs that
88+
-- are identical, except one uses a reflected polynomial and the other a
89+
-- normal (non-reflected) polynomial.
90+
--
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-- The test is performed for all possible combinations of Reflect_Input
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-- and Reflect_Output.
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94+
procedure Test_Bitwise_Reflection (T : in out Test_Fixture) is
95+
Test_Data : constant LibCRC.Byte_Array := (1, 2, 3, 4, 5, 255, 254, 253);
96+
97+
begin
98+
for Reflect_Input in Boolean'Range loop
99+
for Reflect_Output in Boolean'Range loop
100+
declare
101+
package Test_CRC is new LibCRC.CRC_32bit.Bitwise
102+
(Polynomial => Test_Polynomial,
103+
Reflected_Polynomial => False,
104+
Seed => Test_Seed,
105+
Final_XOR => Test_Final_XOR,
106+
Reflect_Input => Reflect_Input,
107+
Reflect_Output => Reflect_Output);
108+
109+
package Test_CRC_Reflected is new LibCRC.CRC_32bit.Bitwise
110+
(Polynomial => LibCRC.CRC_32bit.Bit_Reverse_CRC
111+
(Test_Polynomial),
112+
Reflected_Polynomial => True,
113+
Seed => Test_Seed,
114+
Final_XOR => Test_Final_XOR,
115+
Reflect_Input => Reflect_Input,
116+
Reflect_Output => Reflect_Output);
117+
118+
CRC_1 : Unsigned_32;
119+
CRC_2 : Unsigned_32;
120+
begin
121+
122+
CRC_1 := Test_CRC.Calculate (Test_Data);
123+
CRC_2 := Test_CRC_Reflected.Calculate (Test_Data);
124+
125+
Assert (CRC_1 = CRC_2,
126+
"CRC mismatch for Reflect_Input = "
127+
& Reflect_Input'Image & ", Reflect_Output = "
128+
& Reflect_Output'Image & ":"
129+
& CRC_1'Image & " !="
130+
& CRC_2'Image);
131+
end;
132+
end loop;
133+
end loop;
134+
end Test_Bitwise_Reflection;
135+
136+
------------------
137+
-- Add_To_Suite --
138+
------------------
139+
140+
procedure Add_To_Suite (S : in out Test_Suite'Class) is
141+
begin
142+
S.Add_Test (Caller.Create ("Test table reflection equivalence",
143+
Test_Table_Reflection'Access));
144+
S.Add_Test (Caller.Create ("Test bitwise reflection equivalence",
145+
Test_Bitwise_Reflection'Access));
146+
end Add_To_Suite;
147+
148+
end Reflection_Tests;

‎tests/unit_tests/src/reflection_tests.ads‎

Lines changed: 26 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,26 @@
1+
--
2+
-- Copyright 2025 (C) Daniel King
3+
--
4+
-- SPDX-License-Identifier: Apache-2.0
5+
--
6+
with AUnit.Test_Fixtures;
7+
with AUnit.Test_Suites; use AUnit.Test_Suites;
8+
with AUnit.Test_Caller;
9+
10+
-- These tests verify that the CRC computation produces the same output
11+
-- regardless of whether the reflected table or polynomial is used.
12+
13+
package Reflection_Tests is
14+
15+
type Test_Fixture is new AUnit.Test_Fixtures.Test_Fixture with null record;
16+
17+
procedure Test_Table_Reflection (T : in out Test_Fixture);
18+
procedure Test_Bitwise_Reflection (T : in out Test_Fixture);
19+
20+
procedure Add_To_Suite (S : in out Test_Suite'Class);
21+
22+
private
23+
24+
package Caller is new AUnit.Test_Caller (Test_Fixture);
25+
26+
end Reflection_Tests;

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