memory.rs.html -- source
Description: Source to the Rust file `library/core/src/../../stdarch/crates/core_arch/src/wasm32/memory.rs`.
Keywords: rust, rustlang, rust-lang

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    #[cfg(test)]
    use stdarch_test::assert_instr;

    extern "C" {
        #[link_name = "llvm.wasm.memory.grow.i32"]
        fn llvm_memory_grow(mem: i32, pages: i32) -> i32;
        #[link_name = "llvm.wasm.memory.size.i32"]
        fn llvm_memory_size(mem: i32) -> i32;
    }

    /// Corresponding intrinsic to wasm's [`memory.size` instruction][instr]
    ///
    /// This function, when called, will return the current memory size in units of
    /// pages. The current WebAssembly page size is 65536 bytes (64 KB).
    ///
    /// The argument `mem` is the numerical index of which memory to return the
    /// size of. Note that currently the WebAssembly specification only supports one
    /// memory, so it is required that zero is passed in. The argument is present to
    /// be forward-compatible with future WebAssembly revisions. If a nonzero
    /// argument is passed to this function it will currently unconditionally abort.
    ///
    /// [instr]: http://webassembly.github.io/spec/core/exec/instructions.html#exec-memory-size
    #[inline]
    #[cfg_attr(test, assert_instr("memory.size", mem = 0))]
    #[rustc_args_required_const(0)]
    #[stable(feature = "simd_wasm32", since = "1.33.0")]
    pub fn memory_size(mem: u32) -> usize {
        unsafe {
            if mem != 0 {
                crate::intrinsics::abort();
            }
            llvm_memory_size(0) as usize
        }
    }

    /// Corresponding intrinsic to wasm's [`memory.grow` instruction][instr]
    ///
    /// This function, when called, will attempt to grow the default linear memory
    /// by the specified `delta` of pages. The current WebAssembly page size is
    /// 65536 bytes (64 KB). If memory is successfully grown then the previous size
    /// of memory, in pages, is returned. If memory cannot be grown then
    /// `usize::MAX` is returned.
    ///
    /// The argument `mem` is the numerical index of which memory to return the
    /// size of. Note that currently the WebAssembly specification only supports one
    /// memory, so it is required that zero is passed in. The argument is present to
    /// be forward-compatible with future WebAssembly revisions. If a nonzero
    /// argument is passed to this function it will currently unconditionally abort.
    ///
    /// [instr]: http://webassembly.github.io/spec/core/exec/instructions.html#exec-memory-grow
    #[inline]
    #[cfg_attr(test, assert_instr("memory.grow", mem = 0))]
    #[rustc_args_required_const(0)]
    #[stable(feature = "simd_wasm32", since = "1.33.0")]
    pub fn memory_grow(mem: u32, delta: usize) -> usize {
        unsafe {
            if mem != 0 {
                crate::intrinsics::abort();
            }
            llvm_memory_grow(0, delta as i32) as isize as usize
        }
    }