README.patmos

                             PATMOS NEWLIB README



This is a port of the newlib C library for the Patmos processor. We rely on LLVM
as a compiler, such that all system libraries are compiled to LLVM byte-code
(LLVM BC).


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1. Requirements

 - LLVM and Clang for Patmos
   https://github.com/t-crest/patmos-llvm
   https://github.com/t-crest/patmos-clang

 - really not much else


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2. Configure

In order to configure the build correctly use the following command, assuming
LLVM/Clang are installed unter ${LLVM_DIR}:

  configure  --target=patmos-unknown-unknown-elf AR_FOR_TARGET=${LLVM_DIR}/bin/patmos-llvm-ar \
    RANLIB_FOR_TARGET=${LLVM_DIR}/bin/patmos-llvm-ranlib \
    LD_FOR_TARGET=${LLVM_DIR}/bin/patmos-llvm-ld \
    CC_FOR_TARGET=${LLVM_DIR}/bin/patmos-clang \
    CFLAGS_FOR_TARGET="-target patmos-unknown-unknown-elf -O3" \
    --prefix=${LLVM_DIR}

This overrides some variables in order to use the LLVM tools and the Clang C
compiler to generate LLVM-BC-based library and start-up files for Patmos. The
library is configured to be installed under the LLVM install directory, since
the LLVM/Clang tool chain refers to that location to search for includes and 
libraries.

optional options:
  --enable-newlib-multithread=no
  --disable-newlib-io-float

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3. Build and install

That is simple:
    make && make install

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4. Using Patmos' newlib

The LLVM/Clang tool chain is configured to use Patmos' newlib port by default.
All that needs to be done is to make sure that the Clang compiler generates
Patmos code:

  clang -target patmos-unknown-unknown-elf -o test test.c

This compiles test.c into an LLVM BC file, links that BC file with the
LLVM-BC-based newlib library and start-up files and generates native Patmos code
from there.


Have fun!