How to use syscall.Syscall to call a C function accept/return a structure on Windows

[aihui zhu]

the syscall.Syscall function accept/return only uintptr, how should i deal with structure?

i'm asking this question is because that i want to avoid CGo and use pure Go in my module.

thank you.

[Ian Lance Taylor]

On Sat, Oct 31, 2020 at 2:52 AM aihui zhu <mr.z...@gmail.com> wrote:
>
> the syscall.Syscall function accept/return only uintptr, how should i deal with structure?
>
> i'm asking this question is because that i want to avoid CGo and use pure Go in my module.

What Windows function do you want to call, and what is the structure type?

Ian

[aihui zhu]

for example:

void D2D1MakeRotateMatrix(

  FLOAT             angle,

  D2D1_POINT_2F     center,

  D2D1_MATRIX_3X2_F *matrix

);

and a COM based function: D2D1_SIZE_F ID2D1Bitmap_GetSize();

On Saturday, October 31, 2020 at 11:40:59 PM UTC+8, Ian Lance Taylor wrote:

[Ian Lance Taylor]

On Sat, Oct 31, 2020 at 5:46 PM aihui zhu <mr.z...@gmail.com> wrote:
>
> for example:
>
> void D2D1MakeRotateMatrix(
> FLOAT angle,
> D2D1_POINT_2F center,
> D2D1_MATRIX_3X2_F *matrix
> );
> and a COM based function: D2D1_SIZE_F ID2D1Bitmap_GetSize();

Based on reading
https://docs.microsoft.com/en-us/cpp/build/x64-calling-convention I
think the right way to call this will be to define a variable of type
D2D1MakeRotateMatrix and then pass the address of that variable as the
argument to Bitmap_GetSize. But I haven't tried this or anything.

A simple approach would be to use cgo.

Ian

> On Saturday, October 31, 2020 at 11:40:59 PM UTC+8, Ian Lance Taylor wrote:
>>
>> On Sat, Oct 31, 2020 at 2:52 AM aihui zhu <mr....@gmail.com> wrote:
>> >
>> > the syscall.Syscall function accept/return only uintptr, how should i deal with structure?
>> >
>> > i'm asking this question is because that i want to avoid CGo and use pure Go in my module.
>>
>> What Windows function do you want to call, and what is the structure type?
>>
>> Ian
>

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