From 95dba437d720d6f01ce53733264066a6f18055da Mon Sep 17 00:00:00 2001
From: Dirk Petrautzki <dirk@dirk-petrautzki.de>
Date: Fri, 4 Sep 2020 11:01:45 +0200
Subject: [PATCH] Add support for casting UFixed to SFixed and vice versa
---
README.md | 4 ++--
src/FixedPoints/SFixed.h | 5 +++++
src/FixedPoints/SFixedMemberFunctions.h | 25 ++++++++++++++++++++++---
src/FixedPoints/UFixed.h | 5 +++++
src/FixedPoints/UFixedMemberFunctions.h | 19 +++++++++++++++++++
5 files changed, 53 insertions(+), 5 deletions(-)
diff --git a/README.md b/README.md
index d6173af..8093173 100644
--- a/README.md
+++ b/README.md
@@ -176,11 +176,11 @@ This means that you may write code such as `UFixed<8, 8> value = 0.5;` without i
- `double`.
- The smallest unsigned type capable of holding its integer part. I.e. a type of at least `I` bits.
- Another `UFixed` type of a different scale. E.g. `UFixed<4, 4>` may be converted to `UFixed<8, 8>` and vice versa.
+- Another `SFixed` type of a different scale. E.g. `UFixed<4, 4>` may be converted to `SFixed<7, 8>` and vice versa.
`SFixed<I, F>` is explicitly convertible to:
- `float`.
- `double`.
- The smallest signed type capable of holding its integer part. I.e. a type of at least `I + 1` bits.
- Another `SFixed` type of a different scale. E.g. `SFixed<3, 4>` may be converted to `SFixed<7, 8>` and vice versa.
-
-
+- Another `UFixed` type of a different scale. E.g. `SFixed<3, 4>` may be converted to `UFixed<8, 8>` and vice versa.
diff --git a/src/FixedPoints/SFixed.h b/src/FixedPoints/SFixed.h
index b2aa96d..1d9fab7 100644
--- a/src/FixedPoints/SFixed.h
+++ b/src/FixedPoints/SFixed.h
@@ -22,6 +22,9 @@ FIXED_POINTS_BEGIN_NAMESPACE
// Declaration
//
+template< unsigned IntegerOut, unsigned FractionOut >
+class UFixed; // forward declaration of UFixed for casting between UFixed and SFixed
+
template< unsigned Integer, unsigned Fraction >
class SFixed
{
@@ -102,6 +105,8 @@ public:
template< unsigned IntegerOut, unsigned FractionOut >
constexpr explicit operator SFixed<IntegerOut, FractionOut>() const;
+ template< unsigned IntegerOut, unsigned FractionOut >
+ constexpr explicit operator UFixed<IntegerOut, FractionOut>() const;
static constexpr SFixed fromInternal(const InternalType & value);
diff --git a/src/FixedPoints/SFixedMemberFunctions.h b/src/FixedPoints/SFixedMemberFunctions.h
index e2ab090..43b167f 100644
--- a/src/FixedPoints/SFixedMemberFunctions.h
+++ b/src/FixedPoints/SFixedMemberFunctions.h
@@ -182,14 +182,33 @@ constexpr SFixed<Integer, Fraction>::operator long double() const
template< unsigned Integer, unsigned Fraction >
template< unsigned IntegerOut, unsigned FractionOut >
constexpr SFixed<Integer, Fraction>::operator SFixed<IntegerOut, FractionOut>() const
-{
+{
using OutputType = SFixed<IntegerOut, FractionOut>;
using OutputInternalType = typename OutputType::InternalType;
using OutputShiftType = typename OutputType::ShiftType;
-
+
+ using InputType = SFixed<Integer, Fraction>;
+ using InputShiftType = typename InputType::ShiftType;
+
+ return
+ (FractionOut > FractionSize) ?
+ OutputType::fromInternal(static_cast<OutputInternalType>(static_cast<OutputShiftType>(this->value) << ((FractionOut > FractionSize) ? (FractionOut - FractionSize) : 0))) :
+ (FractionSize > FractionOut) ?
+ OutputType::fromInternal(static_cast<OutputInternalType>(static_cast<InputShiftType>(this->value) >> ((FractionSize > FractionOut) ? (FractionSize - FractionOut) : 0))) :
+ OutputType::fromInternal(this->value);
+}
+
+template< unsigned Integer, unsigned Fraction >
+template< unsigned IntegerOut, unsigned FractionOut >
+constexpr SFixed<Integer, Fraction>::operator UFixed<IntegerOut, FractionOut>() const
+{
+ using OutputType = UFixed<IntegerOut, FractionOut>;
+ using OutputInternalType = typename OutputType::InternalType;
+ using OutputShiftType = typename OutputType::ShiftType;
+
using InputType = SFixed<Integer, Fraction>;
using InputShiftType = typename InputType::ShiftType;
-
+
return
(FractionOut > FractionSize) ?
OutputType::fromInternal(static_cast<OutputInternalType>(static_cast<OutputShiftType>(this->value) << ((FractionOut > FractionSize) ? (FractionOut - FractionSize) : 0))) :
diff --git a/src/FixedPoints/UFixed.h b/src/FixedPoints/UFixed.h
index 64079da..7c64a80 100644
--- a/src/FixedPoints/UFixed.h
+++ b/src/FixedPoints/UFixed.h
@@ -22,6 +22,9 @@ FIXED_POINTS_BEGIN_NAMESPACE
// Declaration
//
+template< unsigned IntegerOut, unsigned FractionOut >
+class SFixed; // forward declaration of SFixed for casting between SFixed and UFixed
+
template< unsigned Integer, unsigned Fraction >
class UFixed
{
@@ -103,6 +106,8 @@ public:
template< unsigned IntegerOut, unsigned FractionOut >
constexpr explicit operator UFixed<IntegerOut, FractionOut>() const;
+ template< unsigned IntegerOut, unsigned FractionOut >
+ constexpr explicit operator SFixed<IntegerOut, FractionOut>() const;
static constexpr UFixed fromInternal(const InternalType & value);
diff --git a/src/FixedPoints/UFixedMemberFunctions.h b/src/FixedPoints/UFixedMemberFunctions.h
index 9f7ddd0..c55cde2 100644
--- a/src/FixedPoints/UFixedMemberFunctions.h
+++ b/src/FixedPoints/UFixedMemberFunctions.h
@@ -189,6 +189,25 @@ constexpr UFixed<Integer, Fraction>::operator UFixed<IntegerOut, FractionOut>()
OutputType::fromInternal(this->value);
}
+template< unsigned Integer, unsigned Fraction >
+template< unsigned IntegerOut, unsigned FractionOut >
+constexpr UFixed<Integer, Fraction>::operator SFixed<IntegerOut, FractionOut>() const
+{
+ using OutputType = SFixed<IntegerOut, FractionOut>;
+ using OutputInternalType = typename OutputType::InternalType;
+ using OutputShiftType = typename OutputType::ShiftType;
+
+ using InputType = UFixed<Integer, Fraction>;
+ using InputShiftType = typename InputType::ShiftType;
+
+ return
+ (FractionOut > FractionSize) ?
+ OutputType::fromInternal(static_cast<OutputInternalType>(static_cast<OutputShiftType>(this->value) << ((FractionOut > FractionSize) ? (FractionOut - FractionSize) : 0))) :
+ (FractionSize > FractionOut) ?
+ OutputType::fromInternal(static_cast<OutputInternalType>(static_cast<InputShiftType>(this->value) >> ((FractionSize > FractionOut) ? (FractionSize - FractionOut) : 0))) :
+ OutputType::fromInternal(this->value);
+}
+
//
// Static Functions
//