
usage: ./configure [ variable=value ]...

This configure script generates the file 'makefile' and the file
'../include/NTL/config.h', based upon the values assigned to the
variables on the command line.


########### Here are the most important variables, and their default values.

CXX=g++              # The C++ compiler

CXXFLAGS=-g -O2      # C++ complilation flags

NATIVE=on            # compiles code targeted to current hardware

TUNE=generic (or x86)# performance-tuning switch

DEF_PREFIX=/usr/local# Default software directory

PREFIX=$(DEF_PREFIX) # Directory in which to install NTL library components
SHARED=off           # Generate a shared library (as well as static)

NTL_THREADS=on       # compile in thread-safe mode
NTL_THREAD_BOOST=on  # compile with thread boosting enabled
NTL_EXCEPTIONS=off   # compile in exception-safe mode

NTL_GMP_LIP=on       # Switch to enable the use of GMP as primary 
                     #   long integer package

GMP_PREFIX=$(DEF_PREFIX) # Directory in which GMP components are installed


NTL_GF2X_LIB=off     # Switch to enable the use of the gf2x package
                     #   for faster arithmetic over GF(2)[X]

GF2X_PREFIX=$(DEF_PREFIX) # Directory in which gf2x components are installed

NTL_STD_CXX11=on     # Build assuming C++11 features

NTL_SAFE_VECTORS=on  # build in "safe vector" mode 

NTL_ENABLE_AVX_FFT=off # implement the small-prime FFT using AVX
                       # instructions...this is experimental at 
                       # moment, and may lead to worse performance

NTL_AVOID_AVX512=off # avoid using 512-bit AVX registers


########## Here are more detailed description of these variables.

########## Basic compilation variables:

CXX=g++

# A C++ compiler, e.g., g++, CC, xlC



CXXFLAGS=-g -O2

# Flags for the C++ compiler. 
# It is highly recommend to avoid things like -O3 and -Ofast.
# These may yield incorrect code.


NATIVE=on

# Flag to target code to current hardware.  Setting this flag  will pass
# -march=native through to the compiler via CXXAUTOFLAGS (if possible).  This
# is the easiest way to exploit the hardware capabilities of your machine to
# their fullest potential.  Note that if CXXFLAGS contains an '-march=XXX'
# option, then NATIVE will be turned off.

TUNE=generic (or x86)

# Switch to determine how various performance options get set
#   auto        make runs a performance-tuning wizard 
#   generic     should be OK for most platforms
#   x86         should be well suited for most x86 platforms
# More choices may be added in the future.
# The default is 'x86' if the configuration script detects that it 
# is running on an x86 machine; otherwise the default is 'generic'.


########## Installation path:

DEF_PREFIX=/usr/local

# Default software directory

PREFIX=$(DEF_PREFIX)

# Set this to the directory in which you want NTL components to be installed.
# When 'make install' is executed, the header files are copied into
# $(PREFIX)/include/NTL, the library itself is copied to
# $(PREFIX)/lib/libntl.a, and the documentation files are copied into
# $(PREFIX)/share/doc/NTL.  Unless you have root permissions when running 'make
# install', you will have to override the default PREFIX value with the name of
# your own local directory.  If you want finer-grained control over where the
# different library components are installed, set the variables INCLUDEDIR,
# LIBDIR, and DOCDIR (see below).

########## Shared library switch:

SHARED=off

# Set this to 'on' if you want to generate a shared library, in addition to a
# static library.   Shared libraries have many advantages, but unfortunately,
# their use is rather less portable than that of good, old-fashioned static
# libraries.  If you set SHARED=on, then the makefile will use a libtool
# script.  By default, the libtool script used is freshly built when you run
# configure.  This libtool script is built using another configure sctipt.
# Currently, you can't pass any arguments to this configure script (but you can
# communicate with it via environment variables, as usual).  
#
# You can use a pre-built libtool command by setting the configuration variable
# LIBTOOL.  You can also build a custom libtool script by running the configure
# script in the subdirectory libtool-origin with specialized arguments.
#
# Note that if SHARED=on, then in addition to using the libtool
# program, the makefile relies on features specific to GNU make.


########## thread safety

NTL_THREADS=on

# Set to 'on' if you want to compile NTL in thread-safe mode.  This requires
# several C++11 features, including atomic types, mutexes, and thread_local
# storage.  Your compiler may not yet support these features.  Setting this
# flag will automatically set the NTL_STD_CXX11 flag (if neither NTL_STD_CXX11
# or NTL_STD_CXX14 is already set). It will also pass -pthread throught to the
# compiler via CXXAUTOFLAGS (if possible).
#
# Turning this flag off will also turn off the NTL_THREAD_BOOST flag.

########## thread boosting

NTL_THREAD_BOOST=on

# Set to 'on' if you want to compile NTL so that is does certain internal
# computations using multiple threads.  
#
# This feature is a work in progress.  As time goes on, more NTL algorithms are
# thread boosted.  See BasicThreadPool documentation file for more details.

########## exceptions

NTL_EXCEPTIONS=off

# Set to 'on' if you want to compile NTL with exceptions enabled.  This
# requires several C++11 features, including lambdas and the new rules for
# exception specifications.  Your compiler may not yet support these feautures.
# Setting this flag will automatically set the NTL_STD_CXX11 flag (if neither
# NTL_STD_CXX11 or NTL_STD_CXX14 is already set).

# With exceptions disabled, any error conditions detected by NTL (including
# memory allocation errors) will result in an error message and a call to
# abort.  Also, if compiling in C++11 mode (or later, see NTL_STD_CXX11), with
# exceptions disabled, certain move constructors and move assignment operators
# will be declared "noexcept".  This can lead to greater efficiency (for
# example, std::vector's take advantage of this to avoid call to copy 
# contructors).

# With exceptions enabled, most error conditions detected by NTL will result in
# an exception being thrown.  NTL will also be compiled in a "thread safe" mode
# that prevents memory leaks (and other problems).  In addition, some move
# constructors and move assignment operators may not be declared "noexcept".

########## GMP variables:

NTL_GMP_LIP=on

# Set to 'off' if you don't want to use GMP, the GNU Multi-Precision package,
# as the primary long integer package.  This will lead to significantly slower
# code, and is not recommended.


GMP_PREFIX=$(DEF_PREFIX)

# If GMP was installed in a standard system directory, e.g., /usr/local, then
# do not set this variable.  Otherwise, if you want to use GMP and GMP was
# installed in a directory <gmp_prefix>, then set GMP_PREFIX=<gmp_prefix>.
# This works if the directory <gmp_prefix>/include contains gmp.h and
# <gmp_prefix>/lib contains libgmp.a.  For finer-grained control, set the
# variables GMP_INCDIR and GMP_LIBDIR instead (see below).


########## GF2X variables:

NTL_GF2X_LIB=off

# Set to 'on' if you want to use the gf2x library for faster arithmetic over
# GF(2)[X] (the NTL class GF2X).

# If you set this flag, please note the following.  If you have installed gf2x
# in a standard "system" location, this is all you have to do.  Otherwise, if
# gf2x is built, but not installed in a standard place, you have to set the
# variable GF2X_PREFIX.


GF2X_PREFIX=$(DEF_PREFIX)

# If gf2x was installed in a standard system directory, e.g., /usr/local, then
# do not set this variable.  Otherwise, if you want to use gf2x and gf2x was
# installed in a directory <gf2x_prefix>, then set GF2X_PREFIX=<gf2x_prefix>.
# This works if the directory <gf2x_prefix>/include contains gf2x.h and
# <gf2x_prefix>/lib contains libgf2x.a.  For finer-grained control, set the
# variables GF2X_INCDIR and GF2X_LIBDIR instead (see below).

########### Language stadards

NTL_STD_CXX11=on     # Build assuming C++11 features
NTL_STD_CXX14=off    # Build assuming C++14 features

# Setting one of these may also result in passing pass either -std=c++11 or
# -std=c++14 through to the compiler via CXXAUTOFLAGS (if it is necessary and
# possible).


############ Safe vector mode

NTL_SAFE_VECTORS=on  # Build in "safe vector mode"

# Build NTL in "safe vector mode", which relaxes the "relocatability"
# requirement for NTL vector types. I expect that at some point in the next
# couple of years, this will be "on" by default.  Setting this flag will
# automatically set the NTL_STD_CXX11 flag (if neither NTL_STD_CXX11 or
# NTL_STD_CXX14 is already set).  See vector documentation file for more
# details.


############ AVX FFT

NTL_ENABLE_AVX_FFT=off # implement the small-prime FFT using AVX
                       # instructions...this is experimental at 
                       # moment, and may lead to worse performance

On machines with AVX2/FMA or AVX512, this will implement the small-prime FFT
using AVX code.  This is still quite experimental, and may lead to worse
performance.  While the FFT itself can run 2-3 times faster, this comes at the
cost of (1) restriction to 50-bit primes (so NTL_SP_NBITS will be set to 50
instead of 60), and (2) the CPU speed may be throttled, slowing down other
operations.  So far, it seems that the only operations that are faster are
arithmetic operations in zz_pX, and only for certain choices of modulus.
Arithmetic operations in ZZ_pX, with large modulus, can run slower with AVX
than without.


########### Avoid 512-bit AVX registers

NTL_AVOID_AVX512=off # avoid using 512-bit AVX registers

Even if available, this will avoid the use of 512-bit AVX registers.  This
affects both Mat<zz_p> operations, as well as the AVX-based FFT (see above).




########### Examples:

# If you are happy with all the default values:

   ./configure

# If your C++ compiler is called icpc:

   ./configure CXX=icpc


# If GMP was installed in a non-standard directory, say,  $HOME/sw:

   ./configure GMP_PREFIX=$HOME/sw 


# If you want to use the options -g and -O for compiling C++,
# just execute

   ./configure "CXXFLAGS=-g -O"

# Note the use of quotes to keep the argument in one piece.


# If you want to use the gf2x library:

   ./configure NTL_GF2X_LIB=on



########### 
########### A little magic
###########

CXXAUTOFLAGS=

# This is a variable that is automagically set by the configuration script.
# These are C++ compiler flags that are selected depending on the choice of
# other configuration options, as well as information gleaned by the
# configuration script about the compiler.  To do this, the configuration
# script attempts to figure out the type of compiler and the default language
# standard supported.  The types of compiler currently recognized are gcc,
# clang, and icc.  For these compilers, the automagic should definitely work.
# For others, your mileage may vary.  The configuration script always prints
# out the value it chooses.  Currently, the following flags may get passed
# through CXXAUTOFLAGS:
#
#   -std=c++11 
#   -std=c++14         if requested explicitly via NTL_STD_CXX11=on or 
#                      NTL_STD_CXX14=on, or implicitly via a request
#                      for a feature that requires C++11
#
#   -pthread           if thread-safety is requested via NTL_THREADS=on 
#                      or NTL_THREAD_BOOST=on
#
#   -fp-model precise  only for the Intel icc compiler (to prevent
#                      non-value-preserving floating point optimizations)
#
# If you explicitly set the value of CXXAUTOFLAGS when invoking the
# configuration script, then it will not change that value.

NOCONTRACT=

# Like the CXXAUTOFLAGS variable, this is set automagically by the
# configuration script, unless you explicitly provide a value.  It is only used
# in compiling the source files that implement the quad_float class and the AVX
# FFT.  For these files only, NTL requires not only that the compiler does not
# perform any non-value-preserving floating point optimizations, but that is
# also does not perform any "contractions" (i.e., emit FMA (fused multiply add)
# instructions.  Currently, it may be set as follows:
# 
#   -ffp-contract=off   for gcc (and possibly clang) compilers 
#
#   -mno-fused-madd     for old gcc compilers that don't support 
#                       -ffp-contract=off
#   -DFP_CONTRACT_OFF   for the Intel icc compiler
#
# The configuation script will make every attempt to ensure that this really
# does disable contractions.  If it doesn't work, a fallback strategy is used
# that should still work (but with a performance penalty).


MAKE_PROG=make

# To set CXXAUTOFLAGS and NOCONTRACT, the configure script actually needs to
# run make.  If you wish to use a non-standard make program for this purpose,
# set this variable to point to that program.



########### Here is a complete list of the remaining variables,
########### with their default values.  These variables are pretty 
########### esoteric, and you will probably never change their
########### default values.

AR=ar
ARFLAGS=ruv
RANLIB=ranlib
LDFLAGS=
LDLIBS=-lm
CPPFLAGS=
LIBTOOL=undefined
LIBTOOL_LINK_FLAGS=
LIBTOOL_LINK_LIBS=undefined

LIBDIR=$(PREFIX)/lib
INCLUDEDIR=$(PREFIX)/include
DOCDIR=$(PREFIX)/share/doc

NTL_TLS_HACK=on

NTL_DISABLE_MOVE_ASSIGN=on
NTL_DISABLE_MOVE=off

NTL_LEGACY_NO_NAMESPACE=off
NTL_LEGACY_INPUT_ERROR=off

NTL_LEGACY_SP_MULMOD=off

NTL_UNSIGNED_LONG_LONG_TYPE=undefined
NTL_CLEAN_INT=off
NTL_CLEAN_PTR=on
NTL_RANGE_CHECK=off
NTL_X86_FIX=off
NTL_NO_X86_FIX=off
NTL_NO_INIT_TRANS=on
NTL_DISABLE_LONGDOUBLE=off
NTL_DISABLE_LONGLONG=off
NTL_DISABLE_LL_ASM=off
NTL_MAXIMIZE_SP_NBITS=off

NTL_SPMM_ULL=off
NTL_FFT_BIGTAB=off
NTL_FFT_LAZYMUL=off
NTL_TBL_REM=off
NTL_AVOID_BRANCHING=off
NTL_GF2X_NOINLINE=off
NTL_GF2X_ALTCODE=off
NTL_GF2X_ALTCODE1=off

GMP_INCDIR=$(GMP_PREFIX)/include
GMP_LIBDIR=$(GMP_PREFIX)/lib

GF2X_INCDIR=$(GF2X_PREFIX)/include
GF2X_LIBDIR=$(GF2X_PREFIX)/lib




########### Here is a more detailed description of these variables.

########### Further compilation variables:


AR=ar

# command to make a library



ARFLAGS=ruv

# arguments for AR



RANLIB=ranlib

# set to echo if you want to disable it completely



LDFLAGS=

# arguments for linker for C++ programs




LDLIBS=-lm

# libraries for linking C++ programs



CPPFLAGS=

# arguments for the C preprocessor

LIBTOOL=undefined

# the libtool command -- only needed if SHARED=on
# if left undefined, a fresh libtool script will be built

LIBTOOL_LINK_FLAGS=

# flags to add to command line when building a shared library
# mainly used to pass the argument "-no-undefined" on cygwin

LIBTOOL_LINK_LIBS=undefined

# libraries to add to the command line when building a shared library.
# mainly used to pass the argument "-lpthread", which NTL's
# configure script will do automatically if SHARED=on and NTL_THREADS=on,
# unless user explicitly provides a value for LIBTOOL_LINK_LIBS.
# the purpose of this is to prevent so-called "underlinking".
# specifically, it allows NTL clients to not pass "-pthread" to the
# compiler when linking their own programs.


########### Details of the compilation process (when SHARED=off)


# When a C++ file foo.c is compiled:
   $(CXX) -I../include $(CPPFLAGS) $(CXXFLAGS) -c foo.c

# When a C++ file foo.c is compiled and linked:
   $(CXX) -I../include $(CPPFLAGS) $(CXXFLAGS) $(LDFLAGS) \ 
      -o foo foo.c $(LDLIBS)

# When the library ntl.a is built
   $(AR) $(ARFLAGS) ntl.a [ object files ]...
   $(RANLIB) ntl.a
# If the ranlib command does not exist, everything will still function OK.



########### Further installation variables:

LIBDIR=$(PREFIX)/lib
INCLUDEDIR=$(PREFIX)/include
DOCDIR=$(PREFIX)/share/doc
# Where to install NTL.
#
# Execution of 'make install' copies header files into $(INCLUDEDIR)/NTL,
# copies the library itself to $(LIBDIR)/libntl.a, and copies the documentation
# files into $(DOCDIR)/NTL.

########## TLS hack

NTL_TLS_HACK=on

# when building NTL with NTL_THREADS=on, if the compiler is gcc-compatible, a
# "TLS hack" may be used to workaround the fact that many compilers do not
# (correctly) implement C++11's thread_local feature.  The workaround is to use
# gcc's more limited __thread feature, and to emulate thread_local semantics
# using pthread routines.
# 
# The configuration script will first check if threads and TLS work with the
# hack, and if not, will try setting NTL_TLS_HACK=off.  You can also turn off
# the hack by setting NTL_TLS_HACK=off.


########## Disabling move semantics

NTL_DISABLE_MOVE_ASSIGN=on
NTL_DISABLE_MOVE=off

# The first flag will disable the generation of move assignment operators for
# Vec<T>, Mat<T>, vec_GF2, and GF2X.  By implication, move assignment operators
# will be disabled as well for many other types (like polynomials).  The second
# flag will disable move constuctors and move assignment operators for all NTL
# types.

# These flags are only relevant in C++11 mode.  They are meant to deal with
# backward compatibility issues for legacy NTL clients that may not deal well
# with automatically generated move operations.  It turns out that move
# semantics can quietly break programs.  See
# http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2010/n3153.htm 
# However, the default now is just to disable move assignment operators for
# those classes where it seems likeliest to cause a problem.  This default will
# likely be changed in the future, so that no move operations are disabled.



########## Legacy switches

NTL_LEGACY_NO_NAMESPACE=off 

# put NTL components in the global namespace



NTL_LEGACY_INPUT_ERROR=off
 
# abort on input errors, instead of just setting the
# "fail bit" of the istream object

NTL_LEGACY_SP_MULMOD=off

# use pre-9.0 interfaces for single-precision MulMod routines.
# See discussion in ZZ.txt for details.



########### Basic Configuration Options:

NTL_UNSIGNED_LONG_LONG_TYPE=undefined

# Name of double-word unsigned integer type.  This is a non-standard type, and
# is called 'long long' by many compilers.  MS C++ calls it 'unsigned __int64'.
#
# Note that the new C99 standard defines the type 'unsigned long long' to be at
# least 64-bits wide.  On 32-bit machines, this is just right.  Although not
# officially part of the C++ standard (which predates C99), it is widely
# supported by C++ compilers, and is likely to be added to the C++ standard.
#
# Unfortunately, 64-bit machines usually define 'unsigned long long' to also be
# 64-bits wide, which is kind of useless.  However, GCC provides a type
# __uint128_t which does the job.
#
# If left undefined, NTL will use some "ifdef magic" to find the type most
# suitable for your machine (based on compiler and word size).



NTL_CLEAN_INT=off

# Setting this to 'on' disables the use of some non-standard integer arithmetic
# which would yield slightly better performance.


NTL_CLEAN_PTR=on

# Setting this to 'on' disables the use of some non-standard pointer arithmetic
# which would yield slightly better performance.  The 'off' setting really just
# invites undefined behavior without any measurable performance benefit. 


NTL_RANGE_CHECK=off

# Setting this to 'on' will generate vector subscript range-check code.  Useful
# for debugging, but it slows things down of course.



NTL_X86_FIX=off

# Set to 'on' to force the "x86 floating point fix", overriding the default
# behavior.  By default, NTL will apply the "fix" if it looks like it is
# necessary, and if it knows how to fix it.  The problem addressed here is that
# x86 processors sometimes run in a mode where FP registers have more precision
# than doubles.  This will cause code in quad_float.c some trouble.  NTL can
# normally automatically detect the problem, and fix it, so you shouldn't need
# to worry about this or the next flag.



NTL_NO_X86_FIX=off

# Set to 'on' to forces no "x86 floating point fix", overriding the default
# behavior.



NTL_NO_INIT_TRANS=on

# When 'off', NTL uses a special code sequence to avoid copying large objects
# in return statements.  However, if your compiler optimizes away the return of
# a *named* local object, this is not necessary, and setting this flag to 'on'
# will result in *slightly* more compact and efficient code.  The C++ standard
# explicitly allows compilers to perform this optimization, and with time, more
# compilers actually do this.  Traditionally, however, most will only avoid
# copying *temporary* objects in return statements, and NTL's default code
# sequence exploits this fact.



NTL_DISABLE_LONGDOUBLE=off

# Explicitly disables use of long double arithmetic 

NTL_DISABLE_LONGLONG=off

# Explicitly disables use of long long arithmetic 

NTL_DISABLE_LL_ASM=off

# Explicitly disables use of inline asm as replacement for
# long long arithmetic

NTL_MAXIMIZE_SP_NBITS=on

# Allows for 62-bit single-precision moduli on 64-bit platforms.  By default,
# such moduli are restricted to 60 bits, which usually gives *slightly* better
# performance across a range of of parameters.





########## Performance Options:


NTL_SPMM_ULL=off

# Implement the MulModPrecon code using "unsigned long long" (or specify
# NTL_UNSIGNED_LONG_LONG_TYPE to override the default).


NTL_FFT_BIGTAB=off

# Precomputed tables are used to store all the roots of unity used in FFT
# computations. 


NTL_FFT_LAZYMUL=off

# When set, a "lazy multiplication" strategy due to David Harvey: see his paper
# "FASTER ARITHMETIC FOR NUMBER-THEORETIC TRANSFORMS".



NTL_TBL_REM=off

# With this flag, some divisions are avoided in the ZZ_pX multiplication
# routines.  



NTL_AVOID_BRANCHING=off

# With this option, branches are replaced at several key points with equivalent
# code using shifts and masks.  Recommended for use with RISC architectures,
# especially ones with deep pipelines and high branch penalities.  Newer x86
# platforms that use conditional move intrictions are slightly faster without
# this option.  When in doubt, turn this option on.




NTL_GF2X_NOINLINE=off

# By default, the low-level GF2X multiplication routine in inlined.  This can
# potentially lead to some trouble on some platforms, and you can override the
# default by setting this flag.




NTL_GF2X_ALTCODE=off

# With this option, the default strategy for implmenting low-level GF2X
# multiplication is replaced with an alternative strategy.  This alternative
# strategy seems to work better on RISC machines with deep pipelines and high
# branch penalties (like a powerpc), but does no better (or even worse) on
# x86s.


NTL_GF2X_ALTCODE1=off

# Yet another alternative implementation for GF2X multiplication.



########## More GMP Options:


GMP_INCDIR=$(GMP_PREFIX)/include
# directory containing gmp.h

GMP_LIBDIR=$(GMP_PREFIX)/lib
# directory containing libgmp.a


####### More gf2x options:

GF2X_INCDIR=$(GF2X_PREFIX)/include
# directory containing gf2x.h

GF2X_LIBDIR=$(GF2X_PREFIX)/lib
# directory containing libgf2x.a

