# FORTRAN version of libff-mmap-semaphore.c **URL:** \ **Category:** Feature Request\ **Created:** [September 3, 2019, 8:36am UTC](https://community.freefem.org/t/fortran-version-of-libff-mmap-semaphore-c/124 "2019-09-03T08:36:26Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![gfnallo](https://avatars.discourse-cdn.com/v4/letter/g/71c47a/32.png) [@gfnallo](https://community.freefem.org/u/gfnallo)\ **Post date:** [September 3, 2019, 8:36am UTC](https://community.freefem.org/t/fortran-version-of-libff-mmap-semaphore-c/124/1 "2019-09-03T08:36:26Z")
Dear FreeFem++ developers, thanks first of all for the great work. I am interested in coupling a (large) Fortran code with a FreeFem++ application. I have been considering several options. As mentioned in the topic title, option 3) is the one I would like to draw your attention to: 1. Data exchange by writing on files (rough, slow and unstable but it requires very little modification to both the Fortran code and the FreeFem++ application) - this is the one I have currently implemented. Nevertheless, loss of synchronization between the two codes and data loss are frequent, so I am not satisfied; 2. Coupling of the two codes by means of an external coupling framework (I have been considering OpenPALM [[https://www.cerfacs.fr/globc/PALM\_WEB/](https://www.cerfacs.fr/globc/PALM_WEB/)]). This is probably the most flexible and robust way, but it is not completely straightforward to implement, and after many attempts I gave up -I am still considering the option of contacting the cerfacs developing team, though…- ; 3. Using the mmap/semaphore feature you mention at paragraph 3.7.3 of the manual. This would be very stable and immediately applicable. The issue with point 3) is that the current version of the library is written in C. It would be great if you could provide a Fortran equivalent for libff-mmap-semaphore.c and libff-mmap-semaphore.h. Do you think it would be possible to do that? Thanks in advance, best regards G. F. ---
**Author:** ![frederichecht](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/frederichecht/32/15_2.png) [@frederichecht](https://community.freefem.org/u/frederichecht)\ **Post date:** [September 3, 2019, 2:06pm UTC](https://community.freefem.org/t/fortran-version-of-libff-mmap-semaphore-c/124/2 "2019-09-03T14:06:37Z")
[fortan\_master.f90.zip](https://community.freefem.org/uploads/short-url/pAyLdEEeaGA6DLBstS9CqAYnzBJ.zip) (1.0 KB) and example in fortran: to compile with the freefem++ source : on ~/ff/ff-git/ ifort fortan\_master.f90 -I~/ff/ff-git/plugin/seq/ ~/ff/ff-git/plugin/seq/libff-mmap-semaphore.o -o fortan\_master brochet:couplage-code-with-ff++ hecht$ ./fortan\_master len 1024 size 1024 ffmmap\_write\_ 1 0.000000 8 – FreeFem++ v4.400001 (Ven 30 aoû 2019 14:21:56 CEST - git v4.4-1-2-g05f06665) Load: lg\_fem lg\_mesh lg\_mesh3 eigenvalue sizestack + 1024 =1808 ( 784 ) len 1024 size 1024 ff status = 1 ffmmap\_write\_ 4622382067542392832 11.000000 0 bb ffsem\_post bb ffsem\_wait After wait … ff 11 1 \*\* ff 11 0.195774 ffmmap\_read\_ 4596221518108646428 0.195774 16 iter 1 0.195773892045254 ffmmap\_write\_ 4622945017495814144 12.000000 0 bb ffsem\_post bb ffsem\_wait After wait … ff 12 1 \*\* ff 12 0.232987 ffmmap\_read\_ 4597562265627791501 0.232987 16 iter 2 0.232987111194351 ffmmap\_write\_ 4623507967449235456 13.000000 0 bb ffsem\_post bb ffsem\_wait After wait … ff 13 1 \*\* ff 13 0.273436 ffmmap\_read\_ 4598597409716504116 0.273436 16 iter 3 0.273436262443371 ffmmap\_write\_ 4624070917402656768 14.000000 0 bb ffsem\_post bb ffsem\_wait After wait … ff 14 1 \*\* ff 14 0.317121 ffmmap\_read\_ 4599384370216871847 0.317121 16 iter 4 0.317121345792311 ffmmap\_write\_ 4624633867356078080 15.000000 0 bb ffsem\_post bb ffsem\_wait After wait … ff 15 1 \*\* ff 15 0.364042 ffmmap\_read\_ 4600229624087637234 0.364042 16 iter 5 0.364042361241174 ffmmap\_write\_ 4625196817309499392 16.000000 0 bb ffsem\_post bb ffsem\_wait After wait … ff 16 1 \*\* ff 16 0.414199 ffmmap\_read\_ 4601133171328800200 0.414199 16 iter 6 0.414199308789958 ffmmap\_write\_ 4625478292286210048 17.000000 0 bb ffsem\_post bb ffsem\_wait After wait … ff 17 1 \*\* ff 17 0.467592 ffmmap\_read\_ 4602095011940360802 0.467592 16 iter 7 0.467592188438664 ffmmap\_write\_ 4625759767262920704 18.000000 0 bb ffsem\_post bb ffsem\_wait After wait … ff 18 1 \*\* ff 18 0.524221 ffmmap\_read\_ 4602896982547482941 0.524221 16 iter 8 0.524221000187289 ffmmap\_write\_ 4626041242239631360 19.000000 0 bb ffsem\_post bb ffsem\_wait After wait … ff 19 1 \*\* ff 19 0.584086 ffmmap\_read\_ 4603436196223660859 0.584086 16 iter 9 0.584085744035839 ffmmap\_write\_ 4626322717216342016 20.000000 0 bb ffsem\_post bb ffsem\_wait After wait … ff 20 1 \*\* ff 20 0.647186 ffmmap\_read\_ 4604004556585037569 0.647186 16 iter 10 0.647186419984308 ffmmap\_write\_ 0 0.000000 8 Fin Master After wait … ff 20 0 Fin FreeFem++ Fin Freefem dans master ---
**Author:** ![gfnallo](https://avatars.discourse-cdn.com/v4/letter/g/71c47a/32.png) [@gfnallo](https://community.freefem.org/u/gfnallo)\ **Post date:** [September 4, 2019, 6:16am UTC](https://community.freefem.org/t/fortran-version-of-libff-mmap-semaphore-c/124/3 "2019-09-04T06:16:45Z")
Dear prof. Hecht, thanks a lot for the very prompt reply and for your explanation. Indeed, once compiled, the functions contained in the library libff-mmap-semaphore.c (thus becoming libff-mmap-semaphore.o) can be easily called from a FORTRAN code such as the one you have kindly provided. It is sufficient to dynamically link the library when compiling the FORTRAN code. This perfectly solved my problem, thanks again! G. F.