copy: Wasm text instruction
Limited availability
This feature is not Baseline because it does not work in some of the most widely-used browsers.
The copy memory instruction copies data from one region of a memory to another.
The instruction does not return a value. If either the source or destination range is out of bounds, the instruction traps.
Syntax
Copy within default memory
wasm
;; Copy data in default memory from [100, 125] to [50, 75]
i32.const 50 ;; Destination address to copy to
i32.const 100 ;; Source address to copy from
i32.const 25 ;; Number of bytes to copy
memory.copy ;; Copy memory
;; Copy in default memory using an S-function
(memory.copy (i32.const 50) (i32.const 100) (i32.const 25))
Copy specified memory (if multi-memory supported)
wasm
;; Copy data in specific memory [100, 125] to [50, 75]
i32.const 50 ;; Destination address to copy to
i32.const 100 ;; Source address to copy from
i32.const 25 ;; Number of bytes to copy
memory.copy (memory 2) ;; Copy memory within memory with index 2
;; Copy within memory referenced by its name
i32.const 50 ;; Destination address to copy to
i32.const 100 ;; Source address to copy from
i32.const 25 ;; Number of bytes to copy
memory.copy (memory $memoryName) ;; Copy memory with memory named "$memoryName"
;; Copy same memory using an S function
(memory.copy (memory $memoryName) (i32.const 50) (i32.const 100) (i32.const 25))
Instructions and opcodes
| Instruction | Binary opcode |
|---|---|
memory.copy |
0xFC 0x0a |
Specifications
| Specification |
|---|
| Unknown specification # syntax-instr-memory |
Browser compatibility
BCD tables only load in the browser
Note:
Memory support in Wasm modules matches the WebAssembly.Memory JavaScript API.
The multiMemory key indicates versions in which copy can be used with a specified memory.