Ok, as far as I can work out emscripten runtime memory (ie: 'memory 0') is laid out like this: App fixed sized static data (ie: BSS/DATA) -> Emscripten Stack (not wasm control flow stack) -> Heap memory. Is this correct?
Top of stack/start of heap memory is defined by the globals __stack_pointer and __heap_base, so if I want to add my own fixed size static data I should start at offset __stack_pointer - STACK_SIZE, and increase the globals __heap_base and __stack_pointer by the size of my own static data. Should this work? Is there any way to determine STACK_SIZE directly from the wasm module? Bye! Mark On Wed, Jun 28, 2023 at 3:19 PM Mark Sibly <marksi...@gmail.com> wrote: > Hi, > > I'm writing a simple wasm compiler for a version of BASIC, and am planning > to link the output with an emscripten coded 'runtime' wasm module. > > I tried to do this once before by adding support for the custom lld > sections earlier, but it turned into a bit of an ordeal (it was over half > the code!) so I gave up. The new plan is to link with an emscripten runtime > at the 'final module' level.This involves loading the emscripten runtime > wasm module, and than appending my compiler output to this to create a new > standalone module. The main idea here is that I wont have to mess with the > emscripten stuff much - I can just add my functions to the end of the > functions table etc. > > The first problem I've encountered though is how to append static/global > data. My code will need to use memory offsets past the end of whatever the > emscripten runtime needs (and before dynamic memory which I guess comes > from the same pool?) and the only way I can think of to do this is to add > pages to the 'memory' import, but the resolution of that would be 64K which > isn't bad I guess but seems excessive. > > Is there any way to be able to tell from looking at a wasm module what the > 'highest' memory address it uses is? I remember C used to have data_start > and data_end (or similar) globals and was hoping emscripten might export > something similar but it doesn't seem to. > > Bye! > Mark > > -- > You received this message because you are subscribed to a topic in the > Google Groups "emscripten-discuss" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/emscripten-discuss/Esy2xhLbEFg/unsubscribe > . > To unsubscribe from this group and all its topics, send an email to > emscripten-discuss+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/emscripten-discuss/4062abb6-e1cb-44b3-887a-333ceb8ed808n%40googlegroups.com > <https://groups.google.com/d/msgid/emscripten-discuss/4062abb6-e1cb-44b3-887a-333ceb8ed808n%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "emscripten-discuss" group. To unsubscribe from this group and stop receiving emails from it, send an email to emscripten-discuss+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/emscripten-discuss/CAK32ozg_E2hR_ZJsSQBHZ%3Dh5yidabQgkybBjc68Y2K-S5%3DooXQ%40mail.gmail.com.
