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Diffstat (limited to 'fluent-bit/lib/wasm-micro-runtime-WAMR-1.2.2/core/iwasm/doc/wasm_exports.MD')
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diff --git a/fluent-bit/lib/wasm-micro-runtime-WAMR-1.2.2/core/iwasm/doc/wasm_exports.MD b/fluent-bit/lib/wasm-micro-runtime-WAMR-1.2.2/core/iwasm/doc/wasm_exports.MD new file mode 100644 index 000000000..70708cde3 --- /dev/null +++ b/fluent-bit/lib/wasm-micro-runtime-WAMR-1.2.2/core/iwasm/doc/wasm_exports.MD @@ -0,0 +1,22 @@ +# Wasm exports +The internal data structure for Wasm exports: + + +## Setup exports for Module +The array data structure pointed by `WASMModule::exports` is setup during loading a module. Basically the runtime will load the exports sections from the module file content, and construct an array of C struct `WASMExport`. + +A `WASMExport` item contains three elements that map the Wasm file exports section structure: +- name: the name shown to external +- kind: total 4 export types: function, globals, memory, table +- index: As all the 4 export types are organized in array, this refers to index in target export type + +## Function exports +### use function exports +function exports are often used in two situations: + 1. **call by host**: runtime API `wasm_runtime_lookup_function` will walk through the array of `WASMModuleInstance::export_functions` and compare the exported name with given target symbol name in the function parameter. If any array item matches the name, it then returns the value of field `function` which points to associated function instance (WASMFunctionInstance) + 2. **import by another module**: During linking multiple modules, the runtime saves the pointer of exported WASMFunctionInstance in the local WASMFunctionInstance of importing module. + +### setup for instance +The data structure pointed by `WASMModuleInstance::export_functions` is set up during instantiating module instance. + +The runtime will walk through the `WASMModule::exports` array and find all the item with kind equal to "function". Create a node of `WASMExportFuncInstance` for each matching, find the associated `WASMFunctionInstance` object and save its address in the field `function`. |