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[原]__ASSEMBLY__的用途

2024-07-11 17:15:43   226人阅读

在Linux Kernel中有些constant需要被C code 跟 assembler共同使用

在用constant的時候，不能單方面給0x1000UL因為assembler無法看這東西。

但是C compiler卻可以。所以使用這個gcc feature.

讓C compiler看到的constant是0x1000UL.

而assembler看起來是0x1000.

6/* Some constant macros are used in both assembler and
7* C code. Therefore we cannot annotate them always with
8* ‘UL‘ and other type specifiers unilaterally. We
9* use the following macros to deal with this.
10*
11* Similarly, _AT() will cast an expression with a type in C, but
12* leave it unchanged in asm.
13*/

ref.

[1] http://code.woboq.org/linux/linux/include/uapi/linux/const.h.html


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