counters.cdl

eCos1.31版

# ====================================================================
#
#      counters.cdl
#
#      configuration data related to the kernel counters and clocks
#
# ====================================================================
#####COPYRIGHTBEGIN####
#                                                                          
# -------------------------------------------                              
# The contents of this file are subject to the Red Hat eCos Public License 
# Version 1.1 (the "License"); you may not use this file except in         
# compliance with the License.  You may obtain a copy of the License at    
# http://www.redhat.com/                                                   
#                                                                          
# Software distributed under the License is distributed on an "AS IS"      
# basis, WITHOUT WARRANTY OF ANY KIND, either express or implied.  See the 
# License for the specific language governing rights and limitations under 
# the License.                                                             
#                                                                          
# The Original Code is eCos - Embedded Configurable Operating System,      
# released September 30, 1998.                                             
#                                                                          
# The Initial Developer of the Original Code is Red Hat.                   
# Portions created by Red Hat are                                          
# Copyright (C) 1998, 1999, 2000 Red Hat, Inc.                             
# All Rights Reserved.                                                     
# -------------------------------------------                              
#                                                                          
#####COPYRIGHTEND####
# ====================================================================
######DESCRIPTIONBEGIN####
#
# Author(s):      jskov
# Original data:  nickg
# Contributors:
# Date:           1999-07-05
#
#####DESCRIPTIONEND####
#
# ====================================================================

cdl_option CYGVAR_KERNEL_COUNTERS_CLOCK {
    display       "Provide real-time clock"
    requires      CYGIMP_KERNEL_INTERRUPTS_DSRS
    default_value 1
    description   "
        On all current target systems the kernel can provide a
        real-time clock. This clock serves two purposes. First it is
        necessary to support clock and alarm related functions.
        Second it is needed to implement timeslicing in some of the
        schedulers including the mlqueue scheduler. If the
        application does not require any of these facilities then it
        is possible to disable the real time clock support
        completely."
}

cdl_component CYGPKG_KERNEL_COUNTERS_CLOCK_OVERRIDE {
    display       "Override default clock settings"
    requires      CYGVAR_KERNEL_COUNTERS_CLOCK
    default_value 0
    description   "
        The kernel has default settings for the clock interrupt
        frequency. These settings will vary from platform to
        platform, but typically there will be a 100 clock interrupts
        every second. It is possible to change this frequency, but
        it requires some knowledge of the target hardware."

    cdl_option CYGNUM_KERNEL_COUNTERS_CLOCK_OVERRIDE_PERIOD {
        display       "Clock hardware initialization value"
        flavor        data
        legal_values  1 to 0x7fffffff
        default_value 9999
        description   "
            During system initialization this value is used to initialize
            the clock hardware. The exact meaning of the value and the
            range of legal values therefore depends on the target hardware,
            and the hardware documentation should be consulted for further
            details. In addition the clock resolution numerator and
            denominator values should be updated. Typical values for
            this option would be 150000 on the MN10300 stdeval1 board,
            15625 on the tx39 jmr3904 board, and 20833 on the powerpc
            cogent board."
    }

    cdl_option CYGNUM_KERNEL_COUNTERS_CLOCK_OVERRIDE_NUMERATOR {
        display       "Clock resolution numerator"
        flavor        data
        legal_values  1 to 0x7fffffff
        default_value 1000000000
        description   "
            If a non-default clock interrupt frequency is used then it
            is necessary to specify the clock resolution explicitly.
            This resolution involves two separate values, the numerator
            and the denominator. The result of dividing the numerator by
            the denominator should correspond to the number of
            nanoseconds between clock interrupts. For example a
            numerator of 1000000000 and a denominator of 100 means that
            there are 10000000 nanoseconds (or 10 milliseconds) between
            clock interrupts. Expressing the resolution as a fraction
            should minimize clock drift even for frequencies that cannot
            be expressed as a simple integer. For example a frequency of
            60Hz corresponds to a clock resolution of 16666666.66...
            nanoseconds. This can be expressed accurately as 1000000000
            over 60."
    }

    cdl_option CYGNUM_KERNEL_COUNTERS_CLOCK_OVERRIDE_DENOMINATOR {
        display       "Clock resolution denominator"
        flavor        data
        legal_values  1 to 0x7fffffff
        default_value 100
        description   "
            If a non-default clock interrupt frequency is used then it
            is necessary to specify the clock resolution explicitly.
            This resolution involves two separate values, the numerator
            and the denominator. The result of dividing the numerator by
            the denominator should correspond to the number of
            nanoseconds between clock interrupts. For example a
            numerator of 1000000000 and a denominator of 100 means that
            there are 10000000 nanoseconds (or 10 milliseconds) between
            clock interrupts. Expressing the resolution as a fraction
            should minimize clock drift even for frequencies that cannot
            be expressed as a simple integer. For example a frequency of
            60Hz corresponds to a clock resolution of 16666666.66...
            nanoseconds. This can be expressed accurately as 1000000000
            over 60."
    }
}  

cdl_interface CYGINT_KERNEL_COUNTERS {
    requires 1 == CYGINT_KERNEL_COUNTERS
}

# NOTE: these option should really be a single enum.
cdl_option CYGIMP_KERNEL_COUNTERS_SINGLE_LIST {
    display       "Implement counters using a single list"
    default_value 1
    implements    CYGINT_KERNEL_COUNTERS
    description "
        There are two different implementations of the counter
        objects. The first implementation stores all alarms in a
        single linked list. The alternative implementation uses a
        table of linked lists. A single list is more efficient in
        terms of memory usage and is generally adequate when the
        application only makes use of a small number of alarms."
}

cdl_component CYGIMP_KERNEL_COUNTERS_MULTI_LIST {
    display       "Implement counters using a table of lists"
    default_value 0
    implements    CYGINT_KERNEL_COUNTERS
    description   "
        There are two different implementations of the counter
        objects. The first implementation stores all alarms in a
        single linked list. The alternative implementation uses a
        table of linked lists, with the size of the table being a
        separate configurable option. For more complicated
        operations it is better to have a table of lists since this
        reduces the amount of computation whenever the timer goes
        off. Assuming a table size of 8 (the default value) on
        average the timer code will only need to check 1/8 of the
        pending alarms instead of all of them."

    cdl_option CYGNUM_KERNEL_COUNTERS_MULTI_LIST_SIZE {
	display       "Size of counter list table"
	flavor        data
	legal_values  1 to 1024
	default_value 8
	description   "
	    If counters are implemented using an array of linked lists
	    then this option controls the size of the array. A larger
	    size reduces the amount of computation that needs to take
	    place whenever the timer goes off, but requires extra
	    memory."
    }
}

cdl_option CYGIMP_KERNEL_COUNTERS_SORT_LIST {
    display       "Sort the counter list"
    default_value 0
    description   "
        Sorting the counter lists reduces the amount of work that
        has to be done when a counter tick is processed, since the
        next alarm to expire is always at the front of the list.
        However, it makes adding an alarm to the list more expensive
        since a search must be done for the correct place to put it.
        Many alarms are used to implement timeouts, which seldom trigger,
        so it is worthwhile optimizing this case. For this reason
        sorted list are disabled by default."
}

cdl_option CYGVAR_KERNEL_COUNTERS_CLOCK_LATENCY {
    display       "Measure real-time \[clock\] interrupt latency"
    requires      CYGVAR_KERNEL_COUNTERS_CLOCK
    default_value 0
    description   "
    Measure the interrupt latency as seen by the real-time clock
    timer interrupt.  This requires hardware support, defined by
    the HAL_CLOCK_LATENCY() macro."
}

cdl_option CYGVAR_KERNEL_COUNTERS_CLOCK_DSR_LATENCY {
    display       "Measure real-time \[clock\] DSR latency"
    requires      CYGVAR_KERNEL_COUNTERS_CLOCK
    requires      CYGVAR_KERNEL_COUNTERS_CLOCK_LATENCY
    default_value 0
    description   "
          Measure the DSR latency as seen by the real-time clock
          timer interrupt.  This requires hardware support, defined by
          the HAL_CLOCK_LATENCY() macro."
}

cdl_option CYGNUM_KERNEL_COUNTERS_RTC_RESOLUTION {
    display       "RTC resolution"
    flavor        data
    calculated    { CYGPKG_KERNEL_COUNTERS_CLOCK_OVERRIDE ?                \
                     "{CYGNUM_KERNEL_COUNTERS_CLOCK_OVERRIDE_NUMERATOR,    \
                      CYGNUM_KERNEL_COUNTERS_CLOCK_OVERRIDE_DENOMINATOR}"  \
                    : "{CYGNUM_HAL_RTC_NUMERATOR, CYGNUM_HAL_RTC_DENOMINATOR}"}
    description   "
	This option automatically defines the tuple which is used to
	initialize the RTC resolution, consisting of a numerator and
	denominator.  For more information, see the option to 
        override default clock settings
	(CYGPKG_KERNEL_COUNTERS_CLOCK_OVERRIDE) and associated options."
}

cdl_option CYGNUM_KERNEL_COUNTERS_RTC_PERIOD {
    display       "RTC period"
    flavor        data
    calculated    { CYGPKG_KERNEL_COUNTERS_CLOCK_OVERRIDE ?                \
                     "CYGNUM_KERNEL_COUNTERS_CLOCK_OVERRIDE_PERIOD"        \
                    : "CYGNUM_HAL_RTC_PERIOD"}
    description   "
	This option automatically defines the RTC period to be used in
	setting the system clock hardware.  For more information, see the
	option to override default clock settings
	(CYGPKG_KERNEL_COUNTERS_CLOCK_OVERRIDE) and associated options."
}