dsp_K EL/IX profile

dsp_K EL/IX compatibility

16 February, 2001

Copyright Notice

Copyright (C) Julian Rose, Sussex, U.K. The software and corresponding documents are distributed under license.
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0. Overview

This document is part of the "digital signal processor kernel" family (dsp_K) software distribution and a licensed DSP_K DESCRIPTION document. It describes the intended EL/IX (and POSIX) compatibility that the dsp_K software shall target. EL/IX is a draft API specification proposed by Cygnus that aims to support development of embedded applications using Linux. The API is strongly based on a subset of both the POSIX.1 and ISO C libraries, but enriched with a few non-standard Linux and GNU extensions.

The specification is arranged into levels and options in order to form profiles, so that an implementation might make a profile statement about EL/IX compatibility. The target dsp_K EL/IX profile is given herein (which shall be regularly reviewed as implementation progresses) and a detailed description of dsp_K can be found in the FAQ.

It should be noted that the term POSIX should be read as POSIX-like throughout its use in dsp_K, since in many cases the proper semantics cannot be guaranteed in a flat memory model. However, the software is a genuine attempt to reproduce the closest behaviour possible and is a pragmatic solution rather than an attempt at theoretic precision.

0.1 Version

This document addresses the EL/IX base API specification draft 1.2 and dsp_K software version 0.6.

1. Levels and Options

1.1 Levels

Levels 1 through 3 are of interest but level 4 is not.

1.2 Options

The following option categories are currently considered of interest for dsp_K (but not all functions are wanted):

o some options are taken at any particular level

m some reduction in semantics are allowed

s signal handling

r real-time support

c compatibility functions

' ' some non-option functions are desirable

Some small part of the following categories are currently considered interesting (but most functions are considered too expensive):

f all file system support and its sub-options (a RAM disk would significantly increase the weight of this option)

l library-only functions (most should be provided outside the kernel, e.g. VDSP libraries)

Currently the following options are not considered of interest:

n network support

t terminal support

M memory management and all its sub-options (malloc & free are covered in option l)

2. POSIX (1003.13) profile

Generally dsp_K shall target a minimal profile to include EL/IX level 1 with some of the signal and compatibility functions. In all cases dsp_K is fully configurable through the application configuration file (dsp_Kcfg.h) such that only those functions required by an application are brought in.

Some functions "are" already provided. Current thinking shows additional functions "shall likely" be provided, "might" be provided, or "none" shall be provided.

2.1 Process primitives

2.1.1 Creation and Execution

The following are provided:

fork

exec

2.1.2 Process termination

The following are provided:

wait

waitpid

_exit

2.1.3 Signals

Some of the following are provided and others shall likely be provided:

signal masks

notification mechanisms

real-time signals

kill

sigemptyset

sigfillset

sigaddset

sigdelset

sigismember

sigaction

pthread_sigmask

sigprocmask

sigpending

sigsuspend

sigwait

sigwaitinfo

sigtimedwait

sigqueue

pthread_kill

2.1.4 Timer operations

The following are provided:

alarm

pause

sleep

2.2 Process Envrionment

2.2.1 Process identification

The following are provided:

getpid

getppid

getpgid

setpgid

2.2.2 User identification

none

2.2.3 Process groups

none

2.2.4 System identification

The following are provided:

uname

2.2.5 Time

The following are provided:

time

times (in limited form)

2.2.6 Environment variables

The following are provided:

getenv

2.2.7 Terminal identification

none

2.2.8 Configurable system variables

The following are provided:

sysconf

2.3 Files and Directories

none

2.4 Input and Output Primitives

2.4.1 Pipes

The following are provided:

pipe (to support aio)

2.4.2 File descriptor manipulation

none

2.4.3 Input and Output

The following shall likely be provided:

read (as device driver operations)

write

2.4.4 Control operations on files

none

2.4.5 File synchronisation

none

2.4.6 Asynchronous input and output

The following are provided:

aioread

aiowrite

aiocancel

aiowait

2.5 Device and Class-specific functions

none

2.6 C Language Services

The following are provided:

tzset

asctime_r

ctime_r

gmtime_r

localtime_r

2.7 System databases

none

2.8 Data Interchange Format

none

2.9 Synchronisation

2.9.1 Semaphore functions

The following shall likely be provided:

sem_init

sem_destroy (in modified form)

sem_wait

sem_trywait

sem_post

sem_getvalue

The following might be provided:

sem_open

sem_close

sem_unlink

2.9.2 Mutexes

The following might be provided:

pthread_mutexattr_init

pthread_mutexattr_destroy

pthread_mutexattr_getpshared

pthread_mutexattr_setpshared

pthread_mutex_init

pthread_mutex_destroy

pthread_mutex_lock

pthread_mutex_trylock

pthread_mutex_unlock

2.9.3 Condition variables

The following might be provided:

pthread_condattr_init

pthread_condattr_destroy

pthread_condattr_getpshared

pthread_condattr_setpshared

pthread_cond_init

pthread_cond_destroy

pthread_cond_signal

pthread_cond_broadcast

pthread_cond_wait

pthread_cond_timedwait

2.10 Memory management

none (malloc & free are provided elsewhere)

2.11 Execution scheduling

2.11.1 Process scheduling functions

The following shall likely be provided:

sched_setparam

sched_getparam

sched_setscheduler

sched_getscheduler

sched_yield

sched_get_priority_max

sched_get_priority_min

sched_rr_get_intervale

2.11.2 Thread scheduling

The following might be provided:

pthread_attr_setscope

pthread_attr_getscope

pthread_attr_setinheritsched

pthread_attr_getinheritsched

pthread_attr_setschedpolicy

pthread_attr_getschedpolicy

pthread_attr_setschedparam

pthread_attr_getschedparam

pthread_setschedparam

pthread_getschedparam

2.11.3 Synchronisation scheduling

none

2.12 Clocks and Timers

The following are provided:

clock_settime

clock_gettime

clock_getres

timer_create

timer_delete

timer_settime

timer_gettime

nanosleep

2.13 Message Passing

The following shall likely be provided:

mq_send

mq_receive

mq_notify

mq_setattr

mq_getattr

The following might be provided:

mq_open

mq_close

mq_unlink

2.14 Thread Management

The following might be provided:

pthread_attr_init

pthread_attr_destroy

pthread_attr_setstacksize

pthread_attr_getstacksize

pthread_attr_setstackaddr

pthread_attr_getstackaddr

pthread_attr_setdetachstate

pthread_attr_getdetachstate

pthread_create

pthread_join

pthread_detach

pthread_exit

pthread_self

pthread_equal

pthread_once

2.15 Thread Specific Data

none

2.16 Thread Cancellation

The following might be provided:

pthread_cancel

pthread_setcancelstate

pthread_setcanceltype

pthread_testcancel

pthread_cleanup_push

pthread_cleanup_pop

3. C Library Compatibility

3.1 Error Reporting

none

3.2 Memory Allocation

The following (ISO C) are provided:

malloc

free

The following (ISO C) shall likely be provided:

realloc

calloc

3.3 Character Handling

none (all these should be provided by a compiler suite)

3.4 String and Array Utilities

none (all these should be provided by a compiler suite)

3.5 Character Set Handling

none (all these should be provided by a compiler suite)

3.6 Locales

none (all these should be provided by a compiler suite)

3.7 Message Translation

none (all these might be provided by a compiler suite)

3.8 Searching and Sorting

none (all these should be provided by a compiler suite)

3.9 Pattern Matching

none (all these should be provided by a compiler suite)

3.10 Stream I/O

none (all these should be provided by a compiler suite)

3.11 Low Level I/O

3.11.1 General I/O

The following shall likely be provided:

pread

pwrite

The following are provided:

select (as device driver functions)

ioctl

3.11.2 Asynchronous I/O

none (refer to the POSIX versions)

3.12 File System Interface

none

3.13 Pipes and FIFOs

The following might be provided:

popen

pclose

The following are provided:

pipe

3.14 Sockets

none

3.15 Low Level Terminal Interface

none

3.16 Mathematics

none (all these should be provided by a compiler suite or third party DSP libraries)

3.17 Arithmetic

none (all these should be provided by a compiler suite or third party DSP libraries)

3.18 Date and Time

The following are provided (in POSIX form):

clock

difftime

gettimeofday

settimeofday

adjtime

localtime

gmtime

mktime

asctime

ctime

strftime

strptime

3.19 Resource Usage and Limits

none

3.20 Non-Local Exits

none

3.21 Signal Handling

The following are provided:

signal (as a wrapper for the POSIX sigaction, sigprocmask)

raise (as a wrapper for the POSIX kill)

The following might be provided:

sigblock

sigsetmask

3.22 Program Startup and Termination

3.22.1 Program arguments

none

3.22.2 Environment variables

The following are provided:

putenv

getenv

3.22.3 Program Termination

none

3.23 Processes

The following might be provided:

getpriority

setpriority

nice

3.24 Users and Groups

none

3.25 System Information

The following are provided

uname

3.26 System Configuration

none

3.27 Cryptographic Functions

none

3.28 POSIX threads (Linux extensions)

none