store: Wasm text instruction

The store memory instructions, are used to store a number on the stack in a memory.

There are store instructions for storing an i32, i64, f32, and f64 in memory. For the integer numbers, there are separate instruction variants for storing a wide typed number into a narrower number in memory. For example, you can store a 32-bit number into an 8-bit slot in memory using i32.store8. If the number doesn’t fit in the narrower number type it will wrap. All the variants are listed below.

{{EmbedInteractiveExample("pages/wat/store.html", "tabbed-taller")}} 

Syntax

Store in default memory

;; Store value in default memory at particular offset
i32.const 0 ;; stack variable with offset in memory to store the number
i32.const 20 ;; stack variable with the number to store
i32.store ;; store in default memory

;; Store using S-function (same values and offset)
(i32.store (i32.const 0) (i32.const 20))

Store to specified memory (if multi-memory supported)

;; Store in memory referenced by its index
i32.const 0 ;; offset in memory to store the number
i32.const 20 ;; the number to store
i32.store (memory 2)  ;; store in memory with index 2

;; Store in memory referenced by its name
i32.const 0 ;; offset to store the number
i32.const 20 ;; the number to store
i32.store (memory $memoryName)  ;; store in memory with name "$memoryName"

;; Store in same memory using an S function
(i32.store (memory $memoryName) (i32.const 0) (i32.const 20))

Instructions and opcodes

Specifications

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Browser compatibility

[!NOTE] Memory support in Wasm modules matches the WebAssembly.Memory JavaScript API. The multiMemory key indicates versions in which store can be used with a specified memory.

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