* Lepton EDA 1.9.14 announce and misc questions @ 2021-04-20 9:29 Vladimir Zhbanov 2021-04-20 12:47 ` Matt Wette 0 siblings, 1 reply; 6+ messages in thread From: Vladimir Zhbanov @ 2021-04-20 9:29 UTC (permalink / raw) To: guile-user Hi Guile users and devs, I'm the current maintainer of Lepton EDA suite, an about five year old fork of geda-gaf with accent to moving more functionality to Scheme code. I'm not sure if it is acceptable to advertise it here, please let me know if not. I just know several Guix packagers are reading this mailing list and would like to announce a new version of Lepton, 1.9.14 has been released on April, 7: https://github.com/lepton-eda/lepton-eda/releases/tag/1.9.14-20210407 Lepton supports Guile 2.0, 2.2, and 3.0. There are lots of C code involved and one of our current goals is untangling it and moving our Scheme functionality to FFI as much as possible. Hence, the issue I recently stumbled upon. Having the following code: (define-public (sys-data-dirs) "Returns a list of search directories for system data." (let ((pointer (eda_get_system_data_dirs))) (let loop ((num 0) (ls '())) (let ((string-pointer (dereference-pointer (make-pointer (+ (pointer-address pointer) (* num (alignof '*))))))) (if (null-pointer? string-pointer) (reverse ls) (loop (1+ num) (cons (pointer->string string-pointer) ls))))))) is it permissible to use 'alignof' (or 'sizeof') this way here, if at all? Or some pitfalls may exist? The function gets the C array of strings and translates them into a Scheme list. I just don't want to write an additional C layer to process the array, but I'm in doubt if it could shoot me in the foot on some OS/arch combinations. Thanks in advance, Vladimir ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Lepton EDA 1.9.14 announce and misc questions 2021-04-20 9:29 Lepton EDA 1.9.14 announce and misc questions Vladimir Zhbanov @ 2021-04-20 12:47 ` Matt Wette 2021-04-20 13:46 ` Matt Wette 0 siblings, 1 reply; 6+ messages in thread From: Matt Wette @ 2021-04-20 12:47 UTC (permalink / raw) To: guile-user On 4/20/21 2:29 AM, Vladimir Zhbanov wrote: > Hi Guile users and devs, > > I'm the current maintainer of Lepton EDA suite, an about five year > old fork of geda-gaf with accent to moving more functionality to > Scheme code. I'm not sure if it is acceptable to advertise it > here, please let me know if not. I just know several Guix > packagers are reading this mailing list and would like to announce > a new version of Lepton, 1.9.14 has been released on April, 7: > > https://github.com/lepton-eda/lepton-eda/releases/tag/1.9.14-20210407 > > Sweet. Thanks for posting this. I will take a look at your problem. It'll require digging into the eda_..._dirs function. ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Lepton EDA 1.9.14 announce and misc questions 2021-04-20 12:47 ` Matt Wette @ 2021-04-20 13:46 ` Matt Wette 2021-04-20 23:36 ` Vladimir Zhbanov 0 siblings, 1 reply; 6+ messages in thread From: Matt Wette @ 2021-04-20 13:46 UTC (permalink / raw) To: guile-user On 4/20/21 5:47 AM, Matt Wette wrote: > > > On 4/20/21 2:29 AM, Vladimir Zhbanov wrote: >> Hi Guile users and devs, >> >> I'm the current maintainer of Lepton EDA suite, an about five year >> old fork of geda-gaf with accent to moving more functionality to >> Scheme code. I'm not sure if it is acceptable to advertise it >> here, please let me know if not. I just know several Guix >> packagers are reading this mailing list and would like to announce >> a new version of Lepton, 1.9.14 has been released on April, 7: >> >> https://github.com/lepton-eda/lepton-eda/releases/tag/1.9.14-20210407 >> >> > > Sweet. Thanks for posting this. I will take a look at your problem. > It'll require digging into the eda_..._dirs function. > > > The following should work as a complete program on a system w/ glib. You need to first convert the result to a bytevector and then access the elements (pointers) one at a time. Note that we don't know how big the array returned from the C function is. I pick an oversized value of 100. (use-modules (system foreign)) (use-modules (rnrs bytevectors)) (define glib (dynamic-link "libglib-2.0")) (define g-get-system-data-dirs (let ((f (pointer->procedure '* (dynamic-func "g_get_system_data_dirs" glib) (list))) (bv-pointer-ref (cond ((= (sizeof '*) 8) bytevector-u64-native-ref ) ((= (sizeof '*) 4) bytevector-u32-native-ref ) (else (error "hmmm")))) (BIG 100)) (lambda () (let* ((r (f)) (p (pointer->bytevector r (* BIG (sizeof '*))))) (let loop ((ix 0)) (let* ((ad (bv-pointer-ref p ix)) (sp (make-pointer ad))) (if (equal? %null-pointer sp) '() (cons (pointer->string sp) (loop (+ ix (sizeof '*))))))))))) (simple-format #t "~S" (g-get-system-data-dirs)) ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Lepton EDA 1.9.14 announce and misc questions 2021-04-20 13:46 ` Matt Wette @ 2021-04-20 23:36 ` Vladimir Zhbanov 2021-04-21 0:34 ` Matt Wette 0 siblings, 1 reply; 6+ messages in thread From: Vladimir Zhbanov @ 2021-04-20 23:36 UTC (permalink / raw) To: guile-user Hi Matt, On Tue, Apr 20, 2021 at 06:46:27AM -0700, Matt Wette wrote: > > > On 4/20/21 5:47 AM, Matt Wette wrote: > > > > > > On 4/20/21 2:29 AM, Vladimir Zhbanov wrote: > > > Hi Guile users and devs, > > > > > > I'm the current maintainer of Lepton EDA suite, an about five year > > > old fork of geda-gaf with accent to moving more functionality to > > > Scheme code. I'm not sure if it is acceptable to advertise it > > > here, please let me know if not. I just know several Guix > > > packagers are reading this mailing list and would like to announce > > > a new version of Lepton, 1.9.14 has been released on April, 7: > > > > > > https://github.com/lepton-eda/lepton-eda/releases/tag/1.9.14-20210407 > > > > > > > > > > Sweet. Thanks for posting this. I will take a look at your problem. > > It'll require digging into the eda_..._dirs function. > > > > > > > The following should work as a complete program on a system w/ glib. > You need to first convert the result to a bytevector and then access the > elements (pointers) one at a time. Note that we don't know how big the > array returned from the C function is. I pick an oversized value of 100. > > (use-modules (system foreign)) > (use-modules (rnrs bytevectors)) > > (define glib (dynamic-link "libglib-2.0")) > > (define g-get-system-data-dirs > (let ((f (pointer->procedure > '* (dynamic-func "g_get_system_data_dirs" glib) (list))) > (bv-pointer-ref (cond > ((= (sizeof '*) 8) bytevector-u64-native-ref ) > ((= (sizeof '*) 4) bytevector-u32-native-ref ) > (else (error "hmmm")))) > (BIG 100)) > (lambda () > (let* ((r (f)) > (p (pointer->bytevector r (* BIG (sizeof '*))))) > (let loop ((ix 0)) > (let* ((ad (bv-pointer-ref p ix)) > (sp (make-pointer ad))) > (if (equal? %null-pointer sp) > '() > (cons (pointer->string sp) (loop (+ ix (sizeof '*))))))))))) > > (simple-format #t "~S" (g-get-system-data-dirs)) Thank you for your replies! Probably, I missed something here, so I'll try to elaborate a bit on my initial question. The function eda_get_system_data_dirs() mentioned in my first message has the same type, is defined the same way using dynamic-func though in liblepton instead of glib, and works on mostly the same array as glib's g_get_system_data_dirs(). The function I've shown works well and outputs the same results as yours. It simply uses a bit more upper level interface, IIUC. So the first question is: I wonder, if using bytevectors directly adds something here? Another issue is a little more confusing for me. I read in several places that even on the same system different compilators, say gcc and g++, may use different alignment even for basic C types like, say, double. What will they do on different platforms then? May it be that (alignof '*) will be twice greater than (sizeof '*)? In such a case using multiplied sizeof of pointer for searching the location of a pointer in memory would be just dangerous. I used sizeof in the first version of my code but started to doubt if it is correct and how portable it is. Thanks, Vladimir ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Lepton EDA 1.9.14 announce and misc questions 2021-04-20 23:36 ` Vladimir Zhbanov @ 2021-04-21 0:34 ` Matt Wette 2021-04-21 7:53 ` Vladimir Zhbanov 0 siblings, 1 reply; 6+ messages in thread From: Matt Wette @ 2021-04-21 0:34 UTC (permalink / raw) To: guile-user On 4/20/21 4:36 PM, Vladimir Zhbanov wrote: > Hi Matt, > > On Tue, Apr 20, 2021 at 06:46:27AM -0700, Matt Wette wrote: >> >> On 4/20/21 5:47 AM, Matt Wette wrote: >>> >>> On 4/20/21 2:29 AM, Vladimir Zhbanov wrote: >>>> Hi Guile users and devs, >>>> >>>> I'm the current maintainer of Lepton EDA suite, an about five year >>>> old fork of geda-gaf with accent to moving more functionality to >>>> Scheme code. I'm not sure if it is acceptable to advertise it >>>> here, please let me know if not. I just know several Guix >>>> packagers are reading this mailing list and would like to announce >>>> a new version of Lepton, 1.9.14 has been released on April, 7: >>>> >>>> https://github.com/lepton-eda/lepton-eda/releases/tag/1.9.14-20210407 >>>> >>>> >>> Sweet. Thanks for posting this. I will take a look at your problem. >>> It'll require digging into the eda_..._dirs function. >>> >>> >>> >> The following should work as a complete program on a system w/ glib. >> You need to first convert the result to a bytevector and then access the >> elements (pointers) one at a time. Note that we don't know how big the >> array returned from the C function is. I pick an oversized value of 100. >> >> (use-modules (system foreign)) >> (use-modules (rnrs bytevectors)) >> >> (define glib (dynamic-link "libglib-2.0")) >> >> (define g-get-system-data-dirs >> (let ((f (pointer->procedure >> '* (dynamic-func "g_get_system_data_dirs" glib) (list))) >> (bv-pointer-ref (cond >> ((= (sizeof '*) 8) bytevector-u64-native-ref ) >> ((= (sizeof '*) 4) bytevector-u32-native-ref ) >> (else (error "hmmm")))) >> (BIG 100)) >> (lambda () >> (let* ((r (f)) >> (p (pointer->bytevector r (* BIG (sizeof '*))))) >> (let loop ((ix 0)) >> (let* ((ad (bv-pointer-ref p ix)) >> (sp (make-pointer ad))) >> (if (equal? %null-pointer sp) >> '() >> (cons (pointer->string sp) (loop (+ ix (sizeof '*))))))))))) >> >> (simple-format #t "~S" (g-get-system-data-dirs)) > Thank you for your replies! > > Probably, I missed something here, so I'll try to elaborate a bit > on my initial question. The function eda_get_system_data_dirs() > mentioned in my first message has the same type, is defined the > same way using dynamic-func though in liblepton instead of glib, > and works on mostly the same array as glib's > g_get_system_data_dirs(). The function I've shown works well and > outputs the same results as yours. It simply uses a bit more > upper level interface, IIUC. So the first question is: I wonder, > if using bytevectors directly adds something here? > > Another issue is a little more confusing for me. I read in > several places that even on the same system different compilators, > say gcc and g++, may use different alignment even for basic C > types like, say, double. What will they do on different platforms > then? May it be that (alignof '*) will be twice greater than > (sizeof '*)? In such a case using multiplied sizeof of pointer > for searching the location of a pointer in memory would be just > dangerous. I used sizeof in the first version of my code but > started to doubt if it is correct and how portable it is. > > Thanks, > Vladimir > Hey. I used the glib routine because it returns the same form, if I read correctly. The return value is a pointer to a sequence of (C) pointers. On my machine they are 8 bytes each. So, if the function is returning three strings, say, the first 8 bytes will be a pointer to the first string and last 8 bytes (of a total of 32 = 4 * 8) will be zero. You need to access the three 8-byte pointer values as numbers and convert to guile pointers to access the strings. I don't see a way around that. I don't see this being a problem with gcc vs g++. Maybe in structs with mixed types, but not here, IMO. Matt ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Lepton EDA 1.9.14 announce and misc questions 2021-04-21 0:34 ` Matt Wette @ 2021-04-21 7:53 ` Vladimir Zhbanov 0 siblings, 0 replies; 6+ messages in thread From: Vladimir Zhbanov @ 2021-04-21 7:53 UTC (permalink / raw) To: guile-user On Tue, Apr 20, 2021 at 05:34:59PM -0700, Matt Wette wrote: ... > Hey. I used the glib routine because it returns the same form, > if I read correctly. The return value is a pointer to a sequence > of (C) pointers. On my machine they are 8 bytes each. So, if > the function is returning three strings, say, the first 8 bytes will > be a pointer to the first string and last 8 bytes (of a total of 32 > = 4 * 8) will be zero. You need to access the three 8-byte > pointer values as numbers and convert to guile pointers to > access the strings. I don't see a way around that. > > I don't see this being a problem with gcc vs g++. Maybe in > structs with mixed types, but not here, IMO. I'm much relieved to hear it, thank you for your time. Vladimir ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2021-04-21 7:53 UTC | newest] Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-04-20 9:29 Lepton EDA 1.9.14 announce and misc questions Vladimir Zhbanov 2021-04-20 12:47 ` Matt Wette 2021-04-20 13:46 ` Matt Wette 2021-04-20 23:36 ` Vladimir Zhbanov 2021-04-21 0:34 ` Matt Wette 2021-04-21 7:53 ` Vladimir Zhbanov
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