94 lines
2.1 KiB
Go
94 lines
2.1 KiB
Go
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package main
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import "unsafe"
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//go:wasmimport env overlord_emit
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func overlordEmit(eventPtr, eventLen, payloadPtr, payloadLen uint32) int32
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//go:wasmimport env overlord_host_info
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func overlordHostInfo(outPtr, outLen uint32) int32
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var heap = make([]byte, 64*1024)
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var heapOffset uint32 = 8
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var hostInfo [1024]byte
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var hostInfoLen uint32
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//go:export overlord_alloc
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func overlordAlloc(size uint32) uint32 {
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if size == 0 {
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size = 1
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}
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ptr := (heapOffset + 7) &^ 7
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next := ptr + size
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if next >= uint32(len(heap)) {
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return 0
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}
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heapOffset = next
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return uint32(uintptr(unsafe.Pointer(&heap[ptr])))
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}
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//go:export overlord_free
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func overlordFree(ptr, size uint32) {
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_, _ = ptr, size
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}
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//go:export overlord_on_load
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func overlordOnLoad(hostPtr, hostLen uint32) int32 {
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n := hostLen
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if n > uint32(len(hostInfo)) {
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n = uint32(len(hostInfo))
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}
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copy(hostInfo[:n], bytesAt(hostPtr, n))
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hostInfoLen = n
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emit("ready", hostInfo[:hostInfoLen])
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return 0
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}
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//go:export overlord_on_event
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func overlordOnEvent(eventPtr, eventLen, payloadPtr, payloadLen uint32) int32 {
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_, _ = payloadPtr, payloadLen
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event := string(bytesAt(eventPtr, eventLen))
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if event != "query_host" {
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return 0
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}
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var buf [1024]byte
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n := overlordHostInfo(uint32(uintptr(unsafe.Pointer(&buf[0]))), uint32(len(buf)))
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if n < 0 {
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emitString("host_info", `{"error":"host info buffer too small"}`)
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return 0
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}
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emit("host_info", buf[:uint32(n)])
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return 0
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}
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//go:export overlord_on_unload
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func overlordOnUnload() {}
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func emitString(event string, payload string) {
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emit(event, []byte(payload))
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}
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func emit(event string, payload []byte) {
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eventBytes := []byte(event)
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var eventPtr uint32
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var payloadPtr uint32
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if len(eventBytes) > 0 {
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eventPtr = uint32(uintptr(unsafe.Pointer(&eventBytes[0])))
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}
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if len(payload) > 0 {
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payloadPtr = uint32(uintptr(unsafe.Pointer(&payload[0])))
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}
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overlordEmit(eventPtr, uint32(len(eventBytes)), payloadPtr, uint32(len(payload)))
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}
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func bytesAt(ptr, length uint32) []byte {
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if length == 0 {
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return nil
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}
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return unsafe.Slice((*byte)(unsafe.Pointer(uintptr(ptr))), length)
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}
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func main() {}
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