http://bugzilla.gdcproject.org/show_bug.cgi?id=172
Jens Bauer <jens-bugzi...@gpio.dk> changed:
What |Removed |Added
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CC| |jens-bugzi...@gpio.dk
--- Comment #1 from Jens Bauer <jens-bugzi...@gpio.dk> ---
Having support for this will be highly appreciated.
Especially weak,alias is important on microcontrollers, which have exception
vectors.
Small C Example (this one is for ARM Cortex-M microcontrollers):
---8<-----8<-----8<-----
#define WA(a) __attribute__((weak, alias(#a)))
#define WE WA(defaultExceptionHandler)
#define WR WA(defaultResetHandler)
typedef void (*const VectorFunc)(void);
static void defaultResetHandler(void) __attribute__((__interrupt__));
/* $0000 System Exception Vector Handlers: */
void WR Reset_Handler(void); /* 1 $0004 Reset */
void WE NMI_Handler(void); /* 2 $0008 Non Maskable Interrupt */
void WE HardFault_Handler(void); /* 3 $000c Hard Fault */
...
...
/* Vector Table */
__attribute__((section(".isr_vector"))) VectorFunc g_pfnVectors[] =
{
(VectorFunc)STACK_ADDRESS, /* 0 $0000 Initial Stack Pointer */
Reset_Handler, /* 1 $0004 Reset Vector */
NMI_Handler, /* 2 $0008 Non Maskable Interrupt Vector */
HardFault_Handler, /* 3 $000c Hard Fault Vector */
...
...
};
static void defaultResetHandler(void)
{
while(1){ asm volatile("wfi"); }
}
--->8----->8----->8-----
The above example demonstrates the use of the section attribute and the use of
the weak+alias attribute.
The weak+alias is used for having default implementations of all the exception
handlers (including Reset_Handler).
This means that the user can just start writing code, but allows customization
in case an implementation, which is either simpler or more advanced than the
provided one is required.
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