RT-Thread_v4.1.1

components/libc/cplusplus/README.md

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+# C++ support for RT-Thread #
+
+This is the C++ component in RT-Thread RTOS. In order to support C++ language, this component
+implement a basic environment, such as new/delete operators.
+
+Because RT-Thread RTOS is used in embedded system mostly, there are some rules for C++ applications:
+
+1. DOES NOT use exception.
+2. DOES NOT use Run-Time Type Information (RTTI).
+3. Template is discouraged and it easily causes code text large.
+4. Static class variables are discouraged. The time and place to call their constructor function could not be precisely controlled and make multi-threaded programming a nightmare.
+5. Multiple inheritance is strongly discouraged, as it can cause intolerable confusion.
+
+About GNU GCC compiler
+
+please add following string in your ld link script:
+
+    // in your .text section
+    PROVIDE(__ctors_start__ = .);
+    /* old GCC version uses .ctors */
+    KEEP(*(SORT(.ctors.*)))
+    KEEP(*(.ctors))
+    /* new GCC version uses .init_array */
+    KEEP (*(SORT(.init_array.*)))
+    KEEP (*(.init_array))
+    PROVIDE(__ctors_end__ = .);
+    
+    . = ALIGN(4);
+    
+    // as a standalone section if you use ARM target.
+    
+    /* The .ARM.exidx section is used for C++ exception handling. */
+    /* .ARM.exidx is sorted, so has to go in its own output section.  */
+    __exidx_start = .;
+    ARM.exidx :
+    {
+        *(.ARM.exidx* .gnu.linkonce.armexidx.*)
+
+        /* This is used by the startup in order to initialize the .data secion */
+        _sidata = .;
+    } > CODE
+    __exidx_end = .;
+    
+    /* .data section which is used for initialized data */
+
+    // in your .data section
+    PROVIDE(__dtors_start__ = .);
+    KEEP(*(SORT(.dtors.*)))
+    KEEP(*(.dtors))
+    PROVIDE(__dtors_end__ = .);
+    
+    . = ALIGN(4);