Initial project import

tools/v/examples/call_v_from_c/.gitignore

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+# Ignore the generated C files in this directory
+*.c

tools/v/examples/call_v_from_c/README.md

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+## A simple example to show how to call a function written in v from c
+
+### Compile as a shared library
+
+#### On Linux:
+
+Step 1: Compile the v code to a shared library using `v -cc gcc -shared v_test_print.v` or
+`v -cc gcc -shared v_test_math.v`.
+
+Step 2: Compile the c file using `gcc test_print.c v_test_print.so -o test_print -Wl,-rpath=.` or
+`gcc test_math.c v_test_math.so -o test_math -Wl,-rpath=.`.
+
+Step 3: Run the compiled c file using `./test_print` or `./test_math`.
+
+
+#### On Mac OSX:
+
+On Mac OSX, libgc can be obtained from homebrew by `brew install libgc`.
+During compiling and/or linking, `-I/usr/local/include -L/usr/local/lib` (for x86_64),
+or `-I/opt/homebrew/include -L/opt/homebrew/lib` (for arm64) can be added depending the arch.
+
+Step 1: Compile the v code to a shared library using `v -cc gcc -shared v_test_print.v` or
+`v -cc gcc -shared v_test_math.v`.
+
+Step 2: Compile the c file using `gcc test_print.c v_test_print.dylib -o test_print` or
+`gcc test_math.c v_test_math.dylib -o test_math`.
+
+Step 3: Run the compiled c file using `LD_LIBRARY_PATH=. ./test_print` or
+`LD_LIBRARY_PATH=. ./test_math`.
+
+#### On Windows:
+
+Step 1: Compile the v code to a shared library using `v -cc gcc -shared v_test_print.v` or
+`v -cc gcc -shared v_test_math.v`.
+
+Step 2: Compile the c file using `gcc test_print.c v_test_print.dll -o test_print.exe` or
+`gcc test_math.c v_test_math.dll -o test_math.exe`.
+
+Step 3: Run the compiled c file using `test_print.exe` or `test_math.exe`.
+
+### Compile as a c file
+
+***Requirements: `libgc` must be installed***
+
+Step 1: Compile the v code to a shared library using
+`v -shared -cc gcc -o v_test_print.c v_test_print.v` or
+`v -shared -cc gcc -o v_test_math.c v_test_math.v`.
+
+*Specifying the output with a `.c` extension will generate the corresponding C source file.*
+
+Step 2: Compile the c file using `gcc test_print.c v_test_print.c -o test_print -lgc` or
+`gcc test_math.c v_test_math.c -o test_math -lgc -lm`.
+
+Step 3: Run the compiled c file using `./test_print` or `./test_math`.

tools/v/examples/call_v_from_c/v_test_math.v

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+// vtest build: false // Check the README.md for detailed information; this file needs special compilation options
+module test_math
+
+import math
+
+@[export: 'square']
+fn calculate_square(i int) int {
+	return i * i
+}
+
+@[export: 'sqrt_of_sum_of_squares']
+fn calculate_sqrt_of_sum_of_squares(x f64, y f64) f64 {
+	return math.sqrt(x * x + y * y)
+}

tools/v/examples/call_v_from_c/v_test_print.v

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+// vtest build: false // Check the README.md for detailed information; this file needs special compilation options
+module test_print
+
+@[export: 'foo']
+fn show_foo(s &char) {
+	println(unsafe { cstring_to_vstring(s) })
+}