====== Building SIS ======
SIS provides a logic synthesis library ''libsis.a'' that is required for Petrify. The following instructions are for [[https://embedded.eecs.berkeley.edu/Alumni/pchong/sis.html|SIS 1.3 Unofficial Distribution]].

<WRAP important center round>
SIS source code needs the following changes to be compatible with modern compilers:
  * Note that ''restrict'' is a keyword now and needs to be replaced, e.g. by ''restrict_var''. This effects the following files: ''espresso/unite.c'', ''sis/espresso/unite.c'', ''sis/minimize/minimize.c''
  * In ''sis/command/filec.c'', change line 15 ''#include <termio.h>'' to ''#include <termios.h>''.
  * In ''sis/io/read_kiss.c'', edit line 13, changing ''read_error()'' to ''read_error(char *, ...)''.
  * In ''sis/pld/act_bdd.c'', move line 151 ''static int compare();'' to line 144.
  * In ''sis/pld/act_ite.c'' move ''static int compare();'' to line 124.
  * In ''sis/pld/xln_merge.c'', move line 299 ''static sm_row *xln_merge_find_neighbor_of_row1_with_minimum_neighbors();'' to line 287.
  * In ''sis/pld/xln_pert_dec.c'', move line 58, ''static int kernel_value();'' to line 50. 
  * In ''sis/Makefile.in'' change line ''&& $(AR) x ../$$I && $(AR) r ../$@ * \'' to ''&& $(AR) x ../$$I && $(AR) r ../$@ *.o \'' (this is necessary for OSX build).
</WRAP>

<WRAP important center round>
While 64-bit SIS can be built with ''CFLAGS=-m64'' or ''--host=x86_64-w64-mingw32'' configure parameter, the produced result is not reliable and often segfaults, especially on Windows and OSX.
</WRAP>

===== for Linux =====
Build 32-bit SIS for Linux as follows:
<code>
./configure CFLAGS=-m32
make
</code>

===== for Windows =====
Cygwin build is smooth, but it introduces an ugly dependency on ''cygwin1.dll'' for compatibility layer. On the other hand, MinGW provides a convenient toolchain for cross-compilation and does not introduce unnecessary dependencies, therefore MinGW will be used to cross-compile for Windows.
  - Install MinGW-W64 in Ubuntu as follows: <code>
sudo apt install mingw-w64
</code>
    * Use ''%%__MINGW32__%%'' macro to distinguish Windows builds.
    * Add ''-lwinmm'' to the linker command: <code>
ifneq ($(findstring mingw32, $(CC)),)
    sis_LDADD = libsis.a -lm -lwinmm
else
    sis_LDADD = libsis.a -lm
endif
</code>
  - The primary goal is to build ''libsis.a'' library for linking with Petrify without compatibility layer of Cygwin or MSYS2. The following changes and sacrifices had to be made for Windows build:
    * As the terminal API is not supported in Windows, all the SIS interactive functionality is excluded from Windows build.
    * Memory management is switched to ''malloc'' instead of default ''sbrk''.
    * Host name is assigned to //"unknown"// as ''gethostname'' function could not be found even when linked with ''-lws2_32'' option.
    * An alternative implementation of signal ''SIGSTOP'' in ''bwd_com.c'' needs ''CloseHandle'' function which however cannot be found at linking. It is commented out which may lead to resource leaks.
    * An alternative implementation of ''SIGALRM'' is based on ''timeSetEvent'' function that requires ''-lwinmm'' at linking.
  - Build 32-bit SIS for Windows as follows:<code>
./configure --host=i686-w64-mingw32
make
</code>

===== for OSX =====
  - Use MacPort to install GCC: <code shell>
sudo port install gcc8 +universal
#sudo port select --list gcc
sudo port select --set gcc mp-gcc8
  - Install Bison and DOS2Unix: <code shell>
sudo port install bison
sudo port install dos2unix
</code>
  - Build 32-bit SIS for OSX as follows:<code>
./configure CFLAGS=-m32
make
</code>