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Started a cmake tutorial

This commit is contained in:
2023-10-29 11:50:48 +01:00
commit 348c4c8a91
130 changed files with 2874 additions and 0 deletions

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add_library(MathFunctions MathFunctions.cxx)
# state that anybody linking to us needs to include the current source dir
# to find MathFunctions.h, while we don't.
target_include_directories(MathFunctions
INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}
)
# should we use our own math functions
option(USE_MYMATH "Use tutorial provided math implementation" ON)
if (USE_MYMATH)
target_compile_definitions(MathFunctions PRIVATE "USE_MYMATH")
# generate Table.h
include(MakeTable.cmake)
# library that just does sqrt
add_library(SqrtLibrary STATIC
mysqrt.cxx
${CMAKE_CURRENT_BINARY_DIR}/Table.h
)
# state that we depend on our binary dir to find Table.h
target_include_directories(SqrtLibrary PRIVATE
${CMAKE_CURRENT_BINARY_DIR}
)
# link SqrtLibrary to tutorial_compiler_flags
target_link_libraries(SqrtLibrary PUBLIC tutorial_compiler_flags)
target_link_libraries(MathFunctions PRIVATE SqrtLibrary)
endif()
# link MathFunctions to tutorial_compiler_flags
target_link_libraries(MathFunctions PUBLIC tutorial_compiler_flags)
# install libs
set(installable_libs MathFunctions tutorial_compiler_flags)
if(TARGET SqrtLibrary)
list(APPEND installable_libs SqrtLibrary)
endif()
install(TARGETS ${installable_libs} DESTINATION lib)
# install include headers
install(FILES MathFunctions.h DESTINATION include)

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# first we add the executable that generates the table
add_executable(MakeTable MakeTable.cxx)
target_link_libraries(MakeTable PRIVATE tutorial_compiler_flags)
# add the command to generate the source code
add_custom_command(
OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/Table.h
COMMAND MakeTable ${CMAKE_CURRENT_BINARY_DIR}/Table.h
DEPENDS MakeTable
)

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// A simple program that builds a sqrt table
#include <cmath>
#include <fstream>
#include <iostream>
int main(int argc, char* argv[])
{
// make sure we have enough arguments
if (argc < 2) {
return 1;
}
std::ofstream fout(argv[1], std::ios_base::out);
const bool fileOpen = fout.is_open();
if (fileOpen) {
fout << "double sqrtTable[] = {" << std::endl;
for (int i = 0; i < 10; ++i) {
fout << sqrt(static_cast<double>(i)) << "," << std::endl;
}
// close the table with a zero
fout << "0};" << std::endl;
fout.close();
}
return fileOpen ? 0 : 1; // return 0 if wrote the file
}

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#include "MathFunctions.h"
#include <cmath>
#ifdef USE_MYMATH
# include "mysqrt.h"
#endif
namespace mathfunctions {
double sqrt(double x)
{
// which square root function should we use?
#ifdef USE_MYMATH
return detail::mysqrt(x);
#else
return std::sqrt(x);
#endif
}
}

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#pragma once
namespace mathfunctions {
double sqrt(double x);
}

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#include "mysqrt.h"
#include <iostream>
// include the generated table
#include "Table.h"
namespace mathfunctions {
namespace detail {
// a hack square root calculation using simple operations
double mysqrt(double x)
{
if (x <= 0) {
return 0;
}
// use the table to help find an initial value
double result = x;
if (x >= 1 && x < 10) {
std::cout << "Use the table to help find an initial value " << std::endl;
result = sqrtTable[static_cast<int>(x)];
}
// do ten iterations
for (int i = 0; i < 10; ++i) {
if (result <= 0) {
result = 0.1;
}
double delta = x - (result * result);
result = result + 0.5 * delta / result;
std::cout << "Computing sqrt of " << x << " to be " << result << std::endl;
}
return result;
}
}
}

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#pragma once
namespace mathfunctions {
namespace detail {
double mysqrt(double x);
}
}