X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=docs%2Fkeep_data_small.txt;h=218d4f2eeb6bbae9019713dfc667f8240bc42c3d;hb=c804d4ec5cb222c842644bb99d9b077f5c6576f2;hp=9fc799646a3ad44a3fcf011d2662a377746c4463;hpb=28a209466f43c22db42dd02baa136ac7ac25069b;p=oweals%2Fbusybox.git diff --git a/docs/keep_data_small.txt b/docs/keep_data_small.txt index 9fc799646..218d4f2ee 100644 --- a/docs/keep_data_small.txt +++ b/docs/keep_data_small.txt @@ -59,7 +59,7 @@ wait Example 1 One example how to reduce global data usage is in -archival/libarchive/decompress_unzip.c: +archival/libarchive/decompress_gunzip.c: /* This is somewhat complex-looking arrangement, but it allows * to place decompressor state either in bss or in @@ -87,7 +87,7 @@ take a look at archival/gzip.c. Here all global data is replaced by single global pointer (ptr_to_globals) to allocated storage. In order to not duplicate ptr_to_globals in every applet, you can -reuse single common one. It is defined in libbb/messages.c +reuse single common one. It is defined in libbb/ptr_to_globals.c as struct globals *const ptr_to_globals, but the struct globals is NOT defined in libbb.h. You first define your own struct: @@ -103,7 +103,15 @@ smaller code. In order to assign it, use SET_PTR_TO_GLOBALS macro: SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); -Typically it is done in _main(). +Typically it is done in _main(). Another variation is +to use stack: + +int _main(...) +{ +#undef G + struct globals G; + memset(&G, 0, sizeof(G)); + SET_PTR_TO_GLOBALS(&G); Now you can reference "globals" by G.a, G.buf and so on, in any function.