Commit df9cdf62 authored by Betsy McPhail's avatar Betsy McPhail Committed by Brad King

Tutorial: Improve Step 5

* Updated output message
* Use 'target_compile_definitions' for HAVE_LOG and HAVE_EXP

Previously, the change from using TutorialConfig.h to
target_compile_definitions happened without explanation as part of Step 8.
parent 442c0f0d
......@@ -13,12 +13,6 @@ target_include_directories(MathFunctions
option(USE_MYMATH "Use tutorial provided math implementation" ON)
if(USE_MYMATH)
# does this system provide the log and exp functions?
include(CheckSymbolExists)
set(CMAKE_REQUIRED_LIBRARIES "m")
check_symbol_exists(log "math.h" HAVE_LOG)
check_symbol_exists(exp "math.h" HAVE_EXP)
# first we add the executable that generates the table
add_executable(MakeTable MakeTable.cxx)
target_link_libraries(MakeTable tutorial_compiler_flags)
......
......@@ -18,8 +18,8 @@ double mysqrt(double x)
// if we have both log and exp then use them
#if defined(HAVE_LOG) && defined(HAVE_EXP)
double result = exp(log(x) * 0.5);
std::cout << "Computing sqrt of " << x << " to be " << result << " using log"
<< std::endl;
std::cout << "Computing sqrt of " << x << " to be " << result
<< " using log and exp" << std::endl;
#else
// use the table to help find an initial value
double result = x;
......
......@@ -18,8 +18,8 @@ double mysqrt(double x)
// if we have both log and exp then use them
#if defined(HAVE_LOG) && defined(HAVE_EXP)
double result = exp(log(x) * 0.5);
std::cout << "Computing sqrt of " << x << " to be " << result << " using log"
<< std::endl;
std::cout << "Computing sqrt of " << x << " to be " << result
<< " using log and exp" << std::endl;
#else
// use the table to help find an initial value
double result = x;
......
......@@ -11,12 +11,6 @@ target_include_directories(MathFunctions
option(USE_MYMATH "Use tutorial provided math implementation" ON)
if(USE_MYMATH)
# does this system provide the log and exp functions?
include(CheckSymbolExists)
set(CMAKE_REQUIRED_LIBRARIES "m")
check_symbol_exists(log "math.h" HAVE_LOG)
check_symbol_exists(exp "math.h" HAVE_EXP)
# first we add the executable that generates the table
add_executable(MakeTable MakeTable.cxx)
......@@ -43,6 +37,19 @@ if(USE_MYMATH)
POSITION_INDEPENDENT_CODE ${BUILD_SHARED_LIBS}
)
target_compile_definitions(MathFunctions PRIVATE "USE_MYMATH")
# does this system provide the log and exp functions?
include(CheckSymbolExists)
set(CMAKE_REQUIRED_LIBRARIES "m")
check_symbol_exists(log "math.h" HAVE_LOG)
check_symbol_exists(exp "math.h" HAVE_EXP)
if(HAVE_LOG AND HAVE_EXP)
target_compile_definitions(SqrtLibrary
PRIVATE "HAVE_LOG" "HAVE_EXP")
endif()
target_link_libraries(MathFunctions PRIVATE SqrtLibrary)
endif()
......
......@@ -18,8 +18,8 @@ double mysqrt(double x)
// if we have both log and exp then use them
#if defined(HAVE_LOG) && defined(HAVE_EXP)
double result = exp(log(x) * 0.5);
std::cout << "Computing sqrt of " << x << " to be " << result << " using log"
<< std::endl;
std::cout << "Computing sqrt of " << x << " to be " << result
<< " using log and exp" << std::endl;
#else
// use the table to help find an initial value
double result = x;
......
......@@ -11,12 +11,6 @@ target_include_directories(MathFunctions
option(USE_MYMATH "Use tutorial provided math implementation" ON)
if(USE_MYMATH)
# does this system provide the log and exp functions?
include(CheckSymbolExists)
set(CMAKE_REQUIRED_LIBRARIES "m")
check_symbol_exists(log "math.h" HAVE_LOG)
check_symbol_exists(exp "math.h" HAVE_EXP)
# first we add the executable that generates the table
add_executable(MakeTable MakeTable.cxx)
target_link_libraries(MakeTable tutorial_compiler_flags)
......
......@@ -18,8 +18,8 @@ double mysqrt(double x)
// if we have both log and exp then use them
#if defined(HAVE_LOG) && defined(HAVE_EXP)
double result = exp(log(x) * 0.5);
std::cout << "Computing sqrt of " << x << " to be " << result << " using log"
<< std::endl;
std::cout << "Computing sqrt of " << x << " to be " << result
<< " using log and exp" << std::endl;
#else
// use the table to help find an initial value
double result = x;
......@@ -38,7 +38,7 @@ double mysqrt(double x)
result = result + 0.5 * delta / result;
std::cout << "Computing sqrt of " << x << " to be " << result << std::endl;
}
#endif
return result;
}
}
......
......@@ -10,12 +10,6 @@ set(CMAKE_CXX_STANDARD_REQUIRED True)
# should we use our own math functions
option(USE_MYMATH "Use tutorial provided math implementation" ON)
# does this system provide the log and exp functions?
include(CheckSymbolExists)
set(CMAKE_REQUIRED_LIBRARIES "m")
check_symbol_exists(log "math.h" HAVE_LOG)
check_symbol_exists(exp "math.h" HAVE_EXP)
# configure a header file to pass some of the CMake settings
# to the source code
configure_file(TutorialConfig.h.in TutorialConfig.h)
......
......@@ -2,13 +2,21 @@ add_library(MathFunctions mysqrt.cxx)
# state that anybody linking to us needs to include the current source dir
# to find MathFunctions.h, while we don't.
# state that we depend on Tutorial_BINARY_DIR but consumers don't, as the
# TutorialConfig.h include is an implementation detail
target_include_directories(MathFunctions
INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}
PRIVATE ${Tutorial_BINARY_DIR}
)
# does this system provide the log and exp functions?
include(CheckSymbolExists)
set(CMAKE_REQUIRED_LIBRARIES "m")
check_symbol_exists(log "math.h" HAVE_LOG)
check_symbol_exists(exp "math.h" HAVE_EXP)
if(HAVE_LOG AND HAVE_EXP)
target_compile_definitions(MathFunctions
PRIVATE "HAVE_LOG" "HAVE_EXP")
endif()
# install rules
install(TARGETS MathFunctions DESTINATION lib)
install(FILES MathFunctions.h DESTINATION include)
#include "MathFunctions.h"
#include "TutorialConfig.h"
#include <iostream>
#include <cmath>
......@@ -14,8 +13,8 @@ double mysqrt(double x)
// if we have both log and exp then use them
#if defined(HAVE_LOG) && defined(HAVE_EXP)
double result = exp(log(x) * 0.5);
std::cout << "Computing sqrt of " << x << " to be " << result << " using log"
<< std::endl;
std::cout << "Computing sqrt of " << x << " to be " << result
<< " using log and exp" << std::endl;
#else
double result = x;
......
......@@ -2,7 +2,3 @@
#define Tutorial_VERSION_MAJOR @Tutorial_VERSION_MAJOR@
#define Tutorial_VERSION_MINOR @Tutorial_VERSION_MINOR@
#cmakedefine USE_MYMATH
// does the platform provide exp and log functions?
#cmakedefine HAVE_LOG
#cmakedefine HAVE_EXP
......@@ -10,12 +10,6 @@ set(CMAKE_CXX_STANDARD_REQUIRED True)
# should we use our own math functions
option(USE_MYMATH "Use tutorial provided math implementation" ON)
# does this system provide the log and exp functions?
include(CheckSymbolExists)
set(CMAKE_REQUIRED_LIBRARIES "m")
check_symbol_exists(log "math.h" HAVE_LOG)
check_symbol_exists(exp "math.h" HAVE_EXP)
# configure a header file to pass some of the CMake settings
# to the source code
configure_file(TutorialConfig.h.in TutorialConfig.h)
......
......@@ -21,10 +21,20 @@ add_library(MathFunctions
# state that we depend on our binary dir to find Table.h
target_include_directories(MathFunctions
INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}
PRIVATE ${Tutorial_BINARY_DIR}
${CMAKE_CURRENT_BINARY_DIR}
PRIVATE ${CMAKE_CURRENT_BINARY_DIR}
)
# does this system provide the log and exp functions?
include(CheckSymbolExists)
set(CMAKE_REQUIRED_LIBRARIES "m")
check_symbol_exists(log "math.h" HAVE_LOG)
check_symbol_exists(exp "math.h" HAVE_EXP)
if(HAVE_LOG AND HAVE_EXP)
target_compile_definitions(MathFunctions
PRIVATE "HAVE_LOG" "HAVE_EXP")
endif()
# install rules
install(TARGETS MathFunctions DESTINATION lib)
install(FILES MathFunctions.h DESTINATION include)
#include "MathFunctions.h"
#include "TutorialConfig.h"
#include <iostream>
// include the generated table
......
......@@ -2,7 +2,3 @@
#define Tutorial_VERSION_MAJOR @Tutorial_VERSION_MAJOR@
#define Tutorial_VERSION_MINOR @Tutorial_VERSION_MINOR@
#cmakedefine USE_MYMATH
// does the platform provide exp and log functions?
#cmakedefine HAVE_LOG
#cmakedefine HAVE_EXP
......@@ -10,12 +10,6 @@ set(CMAKE_CXX_STANDARD_REQUIRED True)
# should we use our own math functions
option(USE_MYMATH "Use tutorial provided math implementation" ON)
# does this system provide the log and exp functions?
include(CheckSymbolExists)
set(CMAKE_REQUIRED_LIBRARIES "m")
check_symbol_exists(log "math.h" HAVE_LOG)
check_symbol_exists(exp "math.h" HAVE_EXP)
# configure a header file to pass some of the CMake settings
# to the source code
configure_file(TutorialConfig.h.in TutorialConfig.h)
......
......@@ -21,10 +21,20 @@ add_library(MathFunctions
# state that we depend on our binary dir to find Table.h
target_include_directories(MathFunctions
INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}
PRIVATE ${Tutorial_BINARY_DIR}
${CMAKE_CURRENT_BINARY_DIR}
PRIVATE ${CMAKE_CURRENT_BINARY_DIR}
)
# does this system provide the log and exp functions?
include(CheckSymbolExists)
set(CMAKE_REQUIRED_LIBRARIES "m")
check_symbol_exists(log "math.h" HAVE_LOG)
check_symbol_exists(exp "math.h" HAVE_EXP)
if(HAVE_LOG AND HAVE_EXP)
target_compile_definitions(MathFunctions
PRIVATE "HAVE_LOG" "HAVE_EXP")
endif()
# install rules
install(TARGETS MathFunctions DESTINATION lib)
install(FILES MathFunctions.h DESTINATION include)
#include "MathFunctions.h"
#include "TutorialConfig.h"
#include <iostream>
// include the generated table
......@@ -17,8 +16,8 @@ double mysqrt(double x)
// if we have both log and exp then use them
#if defined(HAVE_LOG) && defined(HAVE_EXP)
double result = exp(log(x) * 0.5);
std::cout << "Computing sqrt of " << x << " to be " << result << " using log"
<< std::endl;
std::cout << "Computing sqrt of " << x << " to be " << result
<< " using log and exp" << std::endl;
#else
// use the table to help find an initial value
double result = x;
......
......@@ -2,7 +2,3 @@
#define Tutorial_VERSION_MAJOR @Tutorial_VERSION_MAJOR@
#define Tutorial_VERSION_MINOR @Tutorial_VERSION_MINOR@
#cmakedefine USE_MYMATH
// does the platform provide exp and log functions?
#cmakedefine HAVE_LOG
#cmakedefine HAVE_EXP
......@@ -10,12 +10,6 @@ set(CMAKE_CXX_STANDARD_REQUIRED True)
# should we use our own math functions
option(USE_MYMATH "Use tutorial provided math implementation" ON)
# does this system provide the log and exp functions?
include(CheckSymbolExists)
set(CMAKE_REQUIRED_LIBRARIES "m")
check_symbol_exists(log "math.h" HAVE_LOG)
check_symbol_exists(exp "math.h" HAVE_EXP)
# configure a header file to pass the version number only
configure_file(TutorialConfig.h.in TutorialConfig.h)
......
......@@ -26,6 +26,12 @@ target_include_directories(MathFunctions
# and that anything that links to use will get this define
target_compile_definitions(MathFunctions INTERFACE "USE_MYMATH")
# does this system provide the log and exp functions?
include(CheckSymbolExists)
set(CMAKE_REQUIRED_LIBRARIES "m")
check_symbol_exists(log "math.h" HAVE_LOG)
check_symbol_exists(exp "math.h" HAVE_EXP)
if(HAVE_LOG AND HAVE_EXP)
target_compile_definitions(MathFunctions
PRIVATE "HAVE_LOG" "HAVE_EXP")
......
......@@ -16,8 +16,8 @@ double mysqrt(double x)
// if we have both log and exp then use them
#if defined(HAVE_LOG) && defined(HAVE_EXP)
double result = exp(log(x) * 0.5);
std::cout << "Computing sqrt of " << x << " to be " << result << " using log"
<< std::endl;
std::cout << "Computing sqrt of " << x << " to be " << result
<< " using log and exp" << std::endl;
#else
// use the table to help find an initial value
double result = x;
......
......@@ -371,43 +371,81 @@ tutorial assume that they are not common.
If the platform has ``log`` and ``exp`` then we will use them to compute the
square root in the ``mysqrt`` function. We first test for the availability of
these functions using the ``CheckSymbolExists.cmake`` macro in the top-level
CMakeLists file as follows:
CMakeLists. We're going to use the new defines in ``TutorialConfig.h.in``,
so be sure to set them before that file is configured.
.. literalinclude:: Step6/CMakeLists.txt
.. literalinclude:: Step6/MathFunctions/CMakeLists.txt
:language: cmake
:start-after: # does this system provide the log and exp functions?
:end-before: # configure a header file to pass some of the CMake settings
:end-before: if(HAVE_LOG AND HAVE_EXP)
Now let's add these defines to ``TutorialConfig.h.in`` so that we can use them
from ``mysqrt.cxx``:
.. literalinclude:: Step6/TutorialConfig.h.in
:language: c
:start-after: // does the platform provide exp and log functions?
.. code-block:: console
Finally, in the ``mysqrt`` function we can provide an alternate implementation
based on ``log`` and ``exp`` if they are available on the system using the
following code:
// does the platform provide exp and log functions?
#cmakedefine HAVE_LOG
#cmakedefine HAVE_EXP
Modify ``mysqrt.cxx`` to include cmath. Next, in that same file in the
``mysqrt`` function we can provide an alternate implementation based on
``log`` and ``exp`` if they are available on the system using the following
code (don't forget the ``#endif`` before returning the result!):
.. literalinclude:: Step6/MathFunctions/mysqrt.cxx
:language: c++
:start-after: // if we have both log and exp then use them
:end-before: #else
:end-before: // do ten iterations
Run **cmake** or **cmake-gui** to configure the project and then build it
with your chosen build tool.
with your chosen build tool and run the Tutorial executable.
You will notice that we're not using ``log`` and ``exp``, even if we think they
should be available. We should realize quickly that we have forgotten to include
``TutorialConfig.h`` in ``mysqrt.cxx``.
We will also need to update MathFunctions/CMakeLists so ``mysqrt.cxx`` knows
where this file is located:
.. code-block:: cmake
target_include_directories(MathFunctions
INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}
PRIVATE ${CMAKE_BINARY_DIR}
)
After making this update, go ahead and build the project again and run the built
Tutorial executable. If ``log`` and ``exp`` are still not being used, open the
generated ``TutorialConfig.h`` file from the build directory. Maybe they aren't
available on the current system?
Which function gives better results now, sqrt or mysqrt?
Specify Compile Definition
--------------------------
You will notice that even though ``HAVE_LOG`` and ``HAVE_EXP`` are both
defined ``mysqrt`` isn't using them. We should realize quickly that we have
forgotten to include ``TutorialConfig.h`` in ``mysqrt.cxx``.
Is there a better place for us to save the ``HAVE_LOG`` and ``HAVE_EXP`` values
other than in ``TutorialConfig.h``? Let's try to use
``target_compile_definitions``.
After making this update, go ahead and build the project again.
First, remove the defines from ``TutorialConfig.h.in``. We no longer need to
include ``TutorialConfig.h`` from ``mysqrt.cxx`` or the extra include in
MathFunctions/CMakeLists.
Run the built Tutorial executable. Which function gives better results now,
Step1’s sqrt or Step5’s mysqrt?
Next, we can move the check for ``HAVE_LOG`` and ``HAVE_EXP`` to
MathFunctions/CMakeLists and then add specify those values as ``PRIVATE``
compile definitions.
.. literalinclude:: Step6/MathFunctions/CMakeLists.txt
:language: cmake
:start-after: # does this system provide the log and exp functions?
:end-before: # install rules
**Exercise**: Is there a better place for us to save the ``HAVE_LOG`` and
``HAVE_EXP`` values other than in ``TutorialConfig.h``?
After making these updates, go ahead and build the project again. Run the
built Tutorial executable and verify that the results are same as earlier in
this step.
Adding a Custom Command and Generated File (Step 6)
===================================================
......
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