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Re: [Qemu-ppc] [Qemu-devel] [PATCH 02/31] dt: add helpers for 2, 3 and 4
From: |
Alexander Graf |
Subject: |
Re: [Qemu-ppc] [Qemu-devel] [PATCH 02/31] dt: add helpers for 2, 3 and 4 cell adds |
Date: |
Fri, 8 Jun 2012 15:00:56 +0200 |
On 07.06.2012, at 14:13, David Gibson wrote:
> On Thu, Jun 07, 2012 at 01:27:56PM +0200, Alexander Graf wrote:
>>
>> On 07.06.2012, at 01:45, David Gibson wrote:
>>
>>> [snip]
>>>>> You mean internally? Yeah, probably. Externally? The point of these
>>>>> helpers is to make the code look less cluttered. We can already pass in
>>>>> an array just fine, but C is quite annoying about generating those on
>>>>> the fly, while it's easy to pass in ints as parameters :)
>>>>
>>>> Varargs?
>>>
>>> Ugly and risky with standard C varargs (because an explicit length
>>> would be needed). Could be done neatly with gcc macro varargs.
>>
>> Could a combination of both like this work?
>>
>> #include <stdio.h>
>> #include <stdarg.h>
>>
>> #define __VA_NARG__(...) \
>> (__VA_NARG_(_0, ## __VA_ARGS__, __RSEQ_N()) - 1)
>> #define __VA_NARG_(...) \
>> __VA_ARG_N(__VA_ARGS__)
>> #define __VA_ARG_N( \
>> _1, _2, _3, _4, _5, _6, _7, _8, _9,_10, \
>> _11,_12,_13,_14,_15,_16,_17,_18,_19,_20, \
>> _21,_22,_23,_24,_25,_26,_27,_28,_29,_30, \
>> _31,_32,_33,_34,_35,_36,_37,_38,_39,_40, \
>> _41,_42,_43,_44,_45,_46,_47,_48,_49,_50, \
>> _51,_52,_53,_54,_55,_56,_57,_58,_59,_60, \
>> _61,_62,_63,N,...) N
>> #define __RSEQ_N() \
>> 63, 62, 61, 60, \
>> 59, 58, 57, 56, 55, 54, 53, 52, 51, 50, \
>> 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, \
>> 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, \
>> 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, \
>> 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, \
>> 9, 8, 7, 6, 5, 4, 3, 2, 1, 0
>>
>> #define PRINT_ELEMS(fdt, ...) print_elems(fdt, __VA_NARG__(__VA_ARGS__),
>> __VA_ARGS__)
>
> Um.. that might work, but it's ludicrously complicated. If we're
> prepared to use the gcc statement expression extension and we're just
> going to abort on errors like findnode_nofail, it can be done much
> more easily using c99 variadic macros:
>
> #define setprop_ints(fdt, path, prop, ...) \
> do { \
> uint32_t tmp[] = {__VA_ARGS__}; \
>
> if (fdt_setprop(findnode_nofail(fdt, path), prop, \
> tmp, sizeof(tmp)) != 0) { \
> /* error message */ \
> abort(); \
> } \
> } while (0)
Hrm. But here we'd be overloading the name space, no? If anyone passes in
tmp[3] as parameter to setprop_ints, it would conflict with the internal
variable tmp, right?
Alex
- [Qemu-ppc] [PATCH 10/31] PPC: e500: dt: create memory node dynamically, (continued)
- [Qemu-ppc] [PATCH 10/31] PPC: e500: dt: create memory node dynamically, Alexander Graf, 2012/06/05
- [Qemu-ppc] [PATCH 20/31] PPC: e500: dt: start with empty device tree, Alexander Graf, 2012/06/05
- [Qemu-ppc] [PATCH 25/31] Revert "dt: temporarily disable subtree creation failure check", Alexander Graf, 2012/06/05
- [Qemu-ppc] [PATCH 02/31] dt: add helpers for 2, 3 and 4 cell adds, Alexander Graf, 2012/06/05
- Re: [Qemu-ppc] [Qemu-devel] [PATCH 02/31] dt: add helpers for 2, 3 and 4 cell adds, Peter Crosthwaite, 2012/06/06
- Re: [Qemu-ppc] [Qemu-devel] [PATCH 02/31] dt: add helpers for 2, 3 and 4 cell adds, Alexander Graf, 2012/06/06
- Re: [Qemu-ppc] [Qemu-devel] [PATCH 02/31] dt: add helpers for 2, 3 and 4 cell adds, Scott Wood, 2012/06/06
- Re: [Qemu-ppc] [Qemu-devel] [PATCH 02/31] dt: add helpers for 2, 3 and 4 cell adds, David Gibson, 2012/06/06
- Re: [Qemu-ppc] [Qemu-devel] [PATCH 02/31] dt: add helpers for 2, 3 and 4 cell adds, Alexander Graf, 2012/06/07
- Re: [Qemu-ppc] [Qemu-devel] [PATCH 02/31] dt: add helpers for 2, 3 and 4 cell adds, David Gibson, 2012/06/07
- Re: [Qemu-ppc] [Qemu-devel] [PATCH 02/31] dt: add helpers for 2, 3 and 4 cell adds,
Alexander Graf <=
- Re: [Qemu-ppc] [Qemu-devel] [PATCH 02/31] dt: add helpers for 2, 3 and 4 cell adds, David Gibson, 2012/06/08
[Qemu-ppc] [PATCH 18/31] PPC: e500: dt: create global-utils node dynamically, Alexander Graf, 2012/06/05
[Qemu-ppc] [PATCH 21/31] dt: Add -machine dumpdtb option to dump the current dtb, Alexander Graf, 2012/06/05
[Qemu-ppc] [PATCH 31/31] PPC: e500: Refactor serial dt generation, Alexander Graf, 2012/06/05
[Qemu-ppc] [PATCH 05/31] dt: add helper for phandle enumeration, Alexander Graf, 2012/06/05