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diff --git a/zpu/roadshow/roadshow/codesize/index.html b/zpu/roadshow/roadshow/codesize/index.html new file mode 100644 index 0000000..3f61b4e --- /dev/null +++ b/zpu/roadshow/roadshow/codesize/index.html @@ -0,0 +1,58 @@ +<html> +<body> +<h1>Compiling hello world program with the ZPU GCC toolchain</h1> +The ZPU comes with a standard GCC toolchain and an instruction set simulator. This allows compiling, running & debugging simple test programs. The Simulator has +some very basic peripherals defined: counter, timer interrupt and a debug output port. +<h1>Installation</h1> +<ol> +<li>Install Cygwin. http://www.cygwin.com +<li>Start Cygwin bash +<li>unzip zputoolchain.zip +<li>Add install/bin from zputoolchain.zip to PATH.<br> +export PATH=$PATH:<unzipdir>/install/bin +</ol> +<h1>Hello world example</h1> +The ZPU toolchain comes with newlib & libstdc++ support which means that many C/C++ programs can be compiled without modification. +<p> +<code> +zpu-elf-gcc -Os -zeta hello.c -o hello.elf -Wl,--relax -Wl,--gc-sections<br> +zpu-elf-size hello.elf<br> +</code> +<h1>Optimizing for size</h1> +The ZPU toolchain produces highly compact code. +<ol> +<li>Since the ZPU GCC toolchain supports standard ANSI C, it is easy to stumble across +functionality that takes up a lot of space. E.g. the standard printf() function is a beast. Some compilers drop e.g. floating point support +from the printf() function and thus boast a "smaller" printf() when in fact they have a non-standard printf(). newlib has a standard printf() function +and an alternative iprintf() function that works only on integers. +<li>The ZPU ships with default startup code that works across various configurations of the ZPU, so be warned that there is some overhead that will +not occurr in the final application(anywhere between 1-4kBytes). +<li>Compilation and linker options matter. The ZPU benefits greatly from the "-Wl,--relax -Wl,--gc-sections" options which is not used by +all architectures(e.g. GCC ARM does not implement/need -Wl,--relax). +</ol> +<h2>Small code example</h2> +<code> +zpu-elf-gcc -Os -abel smallstd.c -o smallstd.elf -Wl,--relax -Wl,--gc-sections<br> +zpu-elf-size small.elf<br> +<br> +$ zpu-elf-size small.elf<br> + text data bss dec hex filename<br> + 2845 952 36 3833 ef9 small.elf<br> +<br> +</code> + +<h2>Even smaller code example</h2> +If the ZPU implements the optional instructions, the RAM overhead can be reduced significantly. +<p> +<code> +zpu-elf-gcc -Os -abel crt0_phi.S small.c -o small.elf -Wl,--relax -Wl,--gc-sections -nostdlib <br> +zpu-elf-size small.elf<br> +<br> +$ zpu-elf-size small.elf<br> + text data bss dec hex filename<br> + 56 8 0 64 40 small.elf<br> + <br> +</code> + +</body> +</html> |
