This commit aims to make Span implementation more in line with what is present in N4762:
- use appropiate index types where applicable.
- use typedefed type inside the class (index_type, reference, pointer, element_type)
- assertion where applicable
- restrict default construction to Span with extent == 0 or extent == dynamic.
- construct span from a range of pointer
- remove non const overload of the subscript operator
- remove non const overload of the data function
- implement subspan function
- implement missing first and last function of dynamic span
The Span class allows the creation of views over contiguous memory. The view
do not own memory, is typed and has a length. It can be used as a replacement of
the traditional pair of pointer and size in parameters or class fields.
Main operations:
- size(): return the lenght of the memory viewed
- empty(): return if the memory viewed is empty
- [index]: access elements viewed
- data(): return a pointer to the memory viewed.
- first(count): Create a subview from the first count elements.
- last(count): Create a subview from the last count elements.
- == and !=: compare two views or a view to array and return if they are equal or
not.
The Span class came in two flavors:
- Static size: The size is encoded in the Span type and it is as lightweitgh as
a single pointer,
- Dynamic size: The object can store arbitrary views and it costs one pointer
and the size of the view.
Volatile specifier in this case it not required as we currently have all accesses
to the buffer protected by critical section. This shall optimize accesses in
some cases to the buffer.
Fixes#7702
`handle_error` calls `MBED_CALLER_ADDR()`, but this is always a location from within platform/mbed_error.c. This is because `handle_error` is declared static. This does not cause the function to be inlined however. Instead, it is called by each function within mbed_error.c. For example, mbed_error yields this code:
```
000625c8 <mbed_error>:
625c8: b510 push {r4, lr}
625ca: 460c mov r4, r1
625cc: 4611 mov r1, r2
625ce: 461a mov r2, r3
625d0: 9b02 ldr r3, [sp, #8]
625d2: f7ff feff bl 623d4 <handle_error>
625d6: b968 cbnz r0, 625f4 <mbed_error+0x2c>
625d8: 4620 mov r0, r4
625da: f7ff ff67 bl 624ac <print_error_report.constprop.0>
625de: f7ff fea8 bl 62332 <core_util_is_isr_active>
625e2: b910 cbnz r0, 625ea <mbed_error+0x22>
625e4: f7ff fe9f bl 62326 <core_util_are_interrupts_enabled>
625e8: b908 cbnz r0, 625ee <mbed_error+0x26>
625ea: bf30 wfi
625ec: e7fd b.n 625ea <mbed_error+0x22>
625ee: 2001 movs r0, #1
625f0: f000 f948 bl 62884 <__wrap_exit>
625f4: 4800 ldr r0, [pc, #0] ; (625f8 <mbed_error+0x30>)
625f6: bd10 pop {r4, pc}
625f8: 80ff010f .word 0x80ff010f
```
Note that at `625d2` there is a bl to handle error. That replaces the LR, which means that ALL calls to mbed_error will report a location of 0x625d6 or 0x625d7 (user vs. supervisor). I do not expect that this was the intention of the code. The simplest fix is to change line 99:
```C
static inline mbed_error_status_t handle_error(mbed_error_status_t error_status, unsigned int error_value, const char *filename, int line_number)
```
Since `handle_error()` will be inlined, the link register will be kept the same, so `MBED_CALLER_ADDR()` will yield the expected result. However, there is no guarantee that the compiler will respect the `inline` keyword in all circumstances.
The result is that each function that wishes to report its caller must extract its caller. This code cannot be centralised.
I have modified `mbed_error.c` to report the caller of each error reporting function, rather than the error reporting function itself.
I added the powerdown func by GIC in mbed_application because Cortex-A9 use GIC instead of NVIC.
This process prevent unexpected interrupt when updating software by using bootloader.
I added the process for Cortex-A in mbed_application.c because this process was for only Cortex-M.
Also I enabled the macro of MBED_APPLICATION_SUPPORT for Cortex-A.
The new configuration make Error history tracking switched off by default and enabled by using the config flag MBED_CONF_PLATFORM_ERROR_HIST_ENABLED.
Config flag MBED_CONF_PLATFORM_ERROR_ALL_THREADS_INFO enables printing info of all threads. This will be turned off by default.
Vincent Coubard
Martin Kojtal
Cruz Monrreal
Brendan Moran
ccli8
Senthil Ramakrishnan
Deepika
TomoYamanaka