implement timer scheduling as well but as of lwIP 0.5 this is
implemented in a higher layer.
+In addition to the source file providing the functionality of sys_arch,
+the OS emulation layer must provide several header files defining
+macros used throughout lwip. The files required and the macros they
+must define are listed below the sys_arch description.
+
Semaphores can be either counting or binary - lwIP works with both
kinds. Mailboxes are used for message passing and can be implemented
either as a queue which allows multiple messages to be posted to a
- void sys_sem_free(sys_sem_t sem)
- Deallocates a semaphore.
+ Deallocates a semaphore.
- void sys_sem_signal(sys_sem_t sem)
Signals a semaphore.
-- u16_t sys_arch_sem_wait(sys_sem_t sem, u16_t timeout)
+- u32_t sys_arch_sem_wait(sys_sem_t sem, u32_t timeout)
Blocks the thread while waiting for the semaphore to be
signaled. If the "timeout" argument is non-zero, the thread should
Posts the "msg" to the mailbox.
-- u16_t sys_arch_mbox_fetch(sys_mbox_t mbox, void **msg, u16_t timeout)
+- u32_t sys_arch_mbox_fetch(sys_mbox_t mbox, void **msg, u32_t timeout)
Blocks the thread until a message arrives in the mailbox, but does
not block the thread longer than "timeout" milliseconds (similar to
- sys_prot_t sys_arch_protect(void)
-This optional function does a "fast" critical region protection and returns
-the previous protection level. This function is only called during very short
-critical regions. An embedded system which supports ISR-based drivers might
-want to implement this function by disabling interrupts. Task-based systems
-might want to implement this by using a mutex or disabling tasking. This
-function should support recursive calls from the same task or interrupt. In
-other words, sys_arch_protect() could be called while already protected. In
-that case the return value indicates that it is already protected.
+ This optional function does a "fast" critical region protection and returns
+ the previous protection level. This function is only called during very short
+ critical regions. An embedded system which supports ISR-based drivers might
+ want to implement this function by disabling interrupts. Task-based systems
+ might want to implement this by using a mutex or disabling tasking. This
+ function should support recursive calls from the same task or interrupt. In
+ other words, sys_arch_protect() could be called while already protected. In
+ that case the return value indicates that it is already protected.
-sys_arch_protect() is only required if your port is supporting an operating
-system.
+ sys_arch_protect() is only required if your port is supporting an operating
+ system.
- void sys_arch_unprotect(sys_prot_t pval)
-This optional function does a "fast" set of critical region protection to the
-value specified by pval. See the documentation for sys_arch_protect() for
-more information. This function is only required if your port is supporting
-an operating system.
+ This optional function does a "fast" set of critical region protection to the
+ value specified by pval. See the documentation for sys_arch_protect() for
+ more information. This function is only required if your port is supporting
+ an operating system.
+
+-------------------------------------------------------------------------------
+Additional files required for the "OS support" emulation layer:
+-------------------------------------------------------------------------------
+
+cc.h - Architecture environment, some compiler specific, some
+ environment specific (probably should move env stuff
+ to sys_arch.h.)
+
+ Typedefs for the types used by lwip -
+ u8_t, s8_t, u16_t, s16_t, u32_t, s32_t, mem_ptr_t
+
+ Compiler hints for packing lwip's structures -
+ PACK_STRUCT_FIELD(x)
+ PACK_STRUCT_STRUCT
+ PACK_STRUCT_BEGIN
+ PACK_STRUCT_END
+
+ Platform specific diagnostic output -
+ LWIP_PLATFORM_DIAG(x) - non-fatal, print a message.
+ LWIP_PLATFORM_ASSERT(x) - fatal, print message and abandon execution.
+
+ "lightweight" synchronization mechanisms -
+ SYS_ARCH_DECL_PROTECT(x) - declare a protection state variable.
+ SYS_ARCH_PROTECT(x) - enter protection mode.
+ SYS_ARCH_UNPROTECT(x) - leave protection mode.
+
+ If the compiler does not provide memset() this file must include a
+ definition of it, or include a file which defines it.
+
+ This file must either include a system-local <errno.h> which defines
+ the standard *nix error codes, or it should #define LWIP_PROVIDE_ERRNO
+ to make lwip/arch.h define the codes which are used throughout.
+
+
+perf.h - Architecture specific performance measurement.
+ Measurement calls made throughout lwip, these can be defined to nothing.
+ PERF_START - start measuring something.
+ PERF_STOP(x) - stop measuring something, and record the result.
+sys_arch.h - Tied to sys_arch.c
+ Arch dependent types for the following objects:
+ sys_sem_t, sys_mbox_t, sys_thread_t,
+ And, optionally:
+ sys_prot_t
+ Defines to set vars of sys_mbox_t and sys_sem_t to NULL.
+ SYS_MBOX_NULL NULL
+ SYS_SEM_NULL NULL