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doublecall

package
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Published: Oct 26, 2026 License: MIT Imports: 2 Imported by: 0

Documentation

Rendered for windows/amd64

Overview

Package doublecall calls WebView2 COM methods that take a C double BY VALUE (put_ZoomFactor, put_RasterizationScale, put_Expires, the print settings). syscall.SyscallN passes every argument as an integer word, which is only right for such a double on amd64 (the runtime mirrors the call words into XMM0-3) and 386 (stdcall pushes both halves); on arm64 the ABI wants it in d0, which no syscall path can load (golang.org/issue/62583), so Call goes through a runtime.cgocall trampoline there.

Index

Constants

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Variables

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Functions

func Call

func Call(fn uintptr, v float64, args ...uintptr) uintptr

Call invokes HRESULT fn(args..., double v) and returns the HRESULT. args are the integer words that precede the double in the C signature — the interface pointer, plus a by-value aggregate laid out by the caller.

amd64: the double travels as its bit pattern in the next call word; the runtime mirrors the first four words into XMM0-3 (asm_windows_amd64.s), which is where the Windows x64 ABI makes the callee read it.

Types

This section is empty.

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