becker@uiucdcsb.UUCP (11/04/84)
i was wondering if any of you C hackers out there might be able to help me on this: i have a program that generates a rather complex model of an object (this is for computer graphics) that is composed of records. each record contains data and pointers to other records. this entire data structure is irregular. how can i save this structure in a file so that it can be used by another program? keep in mind that this structure is not tree-like in any way; it more closely resembles something a spider did under influence of drugs. thanks, craig becker uiucdcs!uiucdcsb!becker
dave@utcsrgv.UUCP (Dave Sherman) (11/07/84)
In article <19300024@uiucdcsb.UUCP> becker@uiucdcsb.UUCP (Craig Becker) writes:
~|
~| i have a program that generates a rather complex model of an object
~| (this is for computer graphics) that is composed of records. each record
~| contains data and pointers to other records. this entire data structure
~| is irregular. how can i save this structure in a file so that it can
~| be used by another program? keep in mind that this structure is not
~| tree-like in any way; it more closely resembles something a spider did
~| under influence of drugs.
Store all the data in structures declared in consecutive locations
in memory, and save it in a file with a single write(2) call with address
beginning at the start of all the records, and a size large enough to cover
all the data. Read it in the same way. It's cheating, but it works.
Dave Sherman
Toronto
--
{ allegra cornell decvax ihnp4 linus utzoo }!utcsrgv!daveRon Natalie <ron@BRL-TGR> (11/08/84)
The way I did that when I had the problem was to save each item pointers and all into the record (along with the address of each one tacked on to the front of the record). When I loaded them back in, I constructed a table of old-address to new-address mappings. I then went through each one and fixed the pointers. -Ron
rbt@sftig.UUCP (R.Thomas) (11/11/84)
> ~| i have a program that generates a rather complex model of an object > ~| (this is for computer graphics) that is composed of records. each record > ~| contains data and pointers to other records. this entire data structure > ~| is irregular. how can i save this structure in a file so that it can > ~| be used by another program? keep in mind that this structure is not > ~| tree-like in any way; it more closely resembles something a spider did > ~| under influence of drugs. > > Store all the data in structures declared in consecutive locations > in memory, and save it in a file with a single write(2) call with address > beginning at the start of all the records, and a size large enough to cover > all the data. Read it in the same way. It's cheating, but it works. > One more thing that makes this a little easier is to keep all pointers relative to the beginning of the area you will write out. This way you can read it all back in to a different porgram without having to adjust all the pointers for the offset between the old beginning address and the new one. Rick Thomas
greenber@acf4.UUCP (11/13/84)
<> Assuming that you need two or more different programs to access this data, remember to subtract/add the offset of the beginning of these structures BEFORE writing it out to disk and AFTER reading it in. This makes the data "position independent". Another way of doing it (involves more work during the run of the program, though) is to only have offsets to the data in question stored instead of pointers. That is offsets from some arbitrary data address that is at the begiining of your structure and also, again, this requires contiguous structures. Ross M. Greenberg @ NYU ----> allegra!cmcl2!acf4!greenber <----