pass a pointer-to-pointer, or return a pointer? Post: 302274808

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Top Forums Programming pass a pointer-to-pointer, or return a pointer? Post 302274808 by Corona688 on Thursday 8th of January 2009 12:03:59 PM

01-08-2009

Registered User

Quote:

Originally Posted by shamrock

That was true a couple of decades ago. Nowadays most embedded systems mobile phones for ex. have an OS, virtual memory mgmt and all the libraries. Although the op may be using one that is bare bones but I doubt that otherwise he would not be using malloc and would most likely be coding in assembly language instead of in C.

Small microprocessors are more popular than ever, just not for powering all-singing all-dancing java smartphones. They're in things like MP3 players, wireless mice, cordless phones, monitors, thousands of different USB devices, microwaves, cars... you get the idea. And yes, they are very barebones, and yes, C is very popular for programming them for the most part. There's been a huge explosion of different architectures, developers are fortunate to not have to learn the assembler for them all.

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allocb

allocb(9r)																allocb(9r)

NAME

       allocb - STREAMS: Allocates a message block

SYNOPSIS

       #include <sys/stream.h>

       MBLKP allocb(
	       int size,
	       uint pri );

ARGUMENTS

       Specifies the number of bytes in the message block.  Specifies the priority of the request. You use this argument to determine if the allo-
       cation of memory blocks (waits) on the request. If you call the allocb interface at a high priority and it blocks on the request, the  sys-
       tem could deadlock. Typically, you pass the constant BPRI_WAITOK, which signifies that allocb can block. If allocb cannot block, you should
       pass the BPRI_HI constant.

DESCRIPTION

       The allocb interface attempts to allocate a STREAMS message block. Buffer allocation fails only when the system is out of  memory.   If	no
       buffer is available, you can call the bufcall interface, which helps a module recover from a memory allocation failure.

RETURN VALUES

       Upon  successful  completion,  the  allocb interface returns a pointer to the allocated message block. This message block is of type struct
       msgb *. The msgb data structure is defined in the /usr/sys/include/sys/stream.h file.

       If allocb cannot allocate a message block, it returns a NULL pointer.

SEE ALSO

       Kernel Routines: bufcall(9r), esballoc(9r), testb(9r)

       Programmer's Guide: STREAMS

																	allocb(9r)