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Re: [Qemu-devel] [PATCH 00/11] implement 680x0 FPU (part 5)
From: |
Richard Henderson |
Subject: |
Re: [Qemu-devel] [PATCH 00/11] implement 680x0 FPU (part 5) |
Date: |
Fri, 16 Mar 2018 00:24:27 +0800 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 |
On 03/13/2018 04:27 AM, Laurent Vivier wrote:
> I have compared results of these instructions from a real m68040 and from
> QEMU, and they match (sincos differs [1] because in QEMU we compute it as
> sin and cos, and on m68040 sin and cos results differ also with
> sincos results. It looks like a rounding problem, perhaps a bug in m68040
> FPU? or in my test program?)
>
> I know this will need more work, but for the moment I only would
> like to provide these new instructions to the maintream of QEMU.
>
> [1] Example:
>
> sincos -6.125952 -> (0.156586, 0.987664)
>
> QEMU:
>
> sincos c0010000c407cd1182c2bb27 -> 3ffc0000a05812beea449a4d
> 3ffe0000fcd791d65887d19a
> sin c0010000c407cd1182c2bb27 -> 3ffc0000a05812beea449a4d
> cos c0010000c407cd1182c2bb27 -> 3ffe0000fcd791d65887d19a
>
> m68040:
>
> sincos c0010000c407cd1182c2bb27 -> 3ffc0000a05812beea449a4d
> 3ffe0000fcd791d65887d199 <<--
> sin c0010000c407cd1182c2bb27 -> 3ffc0000a05812beea449a4d
> cos c0010000c407cd1182c2bb27 -> 3ffe0000fcd791d65887d19a
Wow, this does seem like a processor bug.
Anyway, I've looked through the patch set and nothing stands out,
Reviewed-by: Richard Henderson <address@hidden>
r~
- [Qemu-devel] [PATCH 02/11] target/m68k: implement fsin, (continued)
- [Qemu-devel] [PATCH 02/11] target/m68k: implement fsin, Laurent Vivier, 2018/03/12
- [Qemu-devel] [PATCH 07/11] target/m68k: implement facos, Laurent Vivier, 2018/03/12
- [Qemu-devel] [PATCH 03/11] target/m68k: implement fcos, Laurent Vivier, 2018/03/12
- [Qemu-devel] [PATCH 08/11] target/m68k: implement fatanh, Laurent Vivier, 2018/03/12
- [Qemu-devel] [PATCH 11/11] target/m68k: implement fcosh, Laurent Vivier, 2018/03/12
- [Qemu-devel] [PATCH 04/11] target/m68k: implement fsincos, Laurent Vivier, 2018/03/12
- [Qemu-devel] [PATCH 06/11] target/m68k: implement fasin, Laurent Vivier, 2018/03/12
- [Qemu-devel] [PATCH 09/11] target/m68k: implement ftanh, Laurent Vivier, 2018/03/12
- [Qemu-devel] [PATCH 05/11] target/m68k: implement fatan, Laurent Vivier, 2018/03/12
- [Qemu-devel] [PATCH 10/11] target/m68k: implement fsinh, Laurent Vivier, 2018/03/12
- Re: [Qemu-devel] [PATCH 00/11] implement 680x0 FPU (part 5),
Richard Henderson <=