[v4,05/21] ipa: libipa: fixedpoint: Fix unsigned usage
diff mbox series

Message ID 20251114005428.90024-6-kieran.bingham@ideasonboard.com
State New
Headers show
Series
  • libipa: Introduce a Quantized type
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Commit Message

Kieran Bingham Nov. 14, 2025, 12:54 a.m. UTC
The fixedToFloatingPoint does not support unsigned Q types, and
incorrectly sign-extends all values which have the top most bit set in
the quantized values.

Fix this by ensuring that only signed types perform sign extension, and
simplify the calcuation for unsigned types.

Convert the storage of the test cases to signed types to correctly
represent their intended purpose, to prevent test failures.

Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
---
 src/ipa/libipa/fixedpoint.h    | 3 +++
 test/ipa/libipa/fixedpoint.cpp | 6 +++---
 2 files changed, 6 insertions(+), 3 deletions(-)

Patch
diff mbox series

diff --git a/src/ipa/libipa/fixedpoint.h b/src/ipa/libipa/fixedpoint.h
index 17db8a026502..d97e6d6135ad 100644
--- a/src/ipa/libipa/fixedpoint.h
+++ b/src/ipa/libipa/fixedpoint.h
@@ -51,6 +51,9 @@  constexpr R fixedToFloatingPoint(T number)
 	static_assert(sizeof(int) >= sizeof(T));
 	static_assert(I + F <= sizeof(T) * 8);
 
+	if constexpr (std::is_unsigned_v<T>)
+		return static_cast<R>(number) / static_cast<R>(1 << F);
+
 	/*
 	 * Recreate the upper bits in case of a negative number by shifting the sign
 	 * bit from the fixed point to the first bit of the unsigned and then right shifting
diff --git a/test/ipa/libipa/fixedpoint.cpp b/test/ipa/libipa/fixedpoint.cpp
index 935412771851..3f2d9ac97fe5 100644
--- a/test/ipa/libipa/fixedpoint.cpp
+++ b/test/ipa/libipa/fixedpoint.cpp
@@ -70,7 +70,7 @@  protected:
 		 * The second 7.992 test is to test that unused bits don't
 		 * affect the result.
 		 */
-		std::map<double, uint16_t> testCases = {
+		std::map<double, int16_t> testCases = {
 			{ 7.992, 0x3ff },
 			{   0.2, 0x01a },
 			{  -0.2, 0x7e6 },
@@ -83,14 +83,14 @@  protected:
 
 		int ret;
 		for (const auto &testCase : testCases) {
-			ret = testSingleFixedPoint<4, 7, uint16_t>(testCase.first,
+			ret = testSingleFixedPoint<4, 7, int16_t>(testCase.first,
 								   testCase.second);
 			if (ret != TestPass)
 				return ret;
 		}
 
 		/* Special case with a superfluous one in the unused bits */
-		ret = testFixedToFloat<4, 7, uint16_t, double>(0xbff, 7.992);
+		ret = testFixedToFloat<4, 7, int16_t, double>(0xbff, 7.992);
 		if (ret != TestPass)
 			return ret;