69 lines
2.1 KiB
V
69 lines
2.1 KiB
V
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module builtin
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import dlmalloc
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// Corresponding intrinsic to wasm’s `memory.grow` instruction
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//
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// This function, when called, will attempt to grow the default linear memory by the specified delta of pages.
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// 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.
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// If memory cannot be grown then -1 is returned.
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//
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// 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,
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// so it is required that zero is passed in. The argument is present to be forward-compatible with future WebAssembly revisions.
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// If a nonzero argument is passed to this function it will currently unconditionally abort
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fn C.__builtin_wasm_memory_grow(mem u32, delta usize) usize
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/// Corresponding intrinsic to wasm's `memory.size` instruction
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///
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/// This function, when called, will return the current memory size in units of
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/// pages. The current WebAssembly page size is 65536 bytes (64 KB).
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fn C.__builtin_wasm_memory_size(mem u32) usize
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const page_size = 65536
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fn system_alloc(_ voidptr, size usize) (voidptr, usize, u32) {
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pages := size / page_size
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prev := C.__builtin_wasm_memory_grow(0, pages)
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if prev == -1 {
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return voidptr(0), 0, 0
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}
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return voidptr(prev * page_size), pages * page_size, 0
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}
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fn system_remap(_ voidptr, _ voidptr, _ usize, _ usize, _ bool) voidptr {
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return voidptr(0)
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}
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fn system_free_part(_ voidptr, _ voidptr, _ usize, _ usize) bool {
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return false
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}
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fn system_free(_ voidptr, _ voidptr, _ usize) bool {
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return false
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}
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fn system_allocates_zeros(_ voidptr) bool {
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return false
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}
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fn system_page_size(_ voidptr) usize {
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return page_size
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}
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fn system_can_release_part(_ voidptr, _ u32) bool {
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return false
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}
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fn get_wasm_allocator() dlmalloc.Allocator {
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return dlmalloc.Allocator{
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alloc: system_alloc
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remap: system_remap
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free_part: system_free_part
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free_: system_free
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can_release_part: system_can_release_part
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allocates_zeros: system_allocates_zeros
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page_size: system_page_size
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data: voidptr(0)
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}
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}
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