ELFv2-ABI/specification/ch_5.xml

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<chapter xmlns="http://docbook.org/ns/docbook"
xmlns:xl="http://www.w3.org/1999/xlink" version="5.0" 
xml:lang="en"
xml:id="dbdoclet.50655243_pgfId-1099317">
  <title>Libraries</title>
  <section xml:id="dbdoclet.50655243___RefHeading___Toc377640665">
    <title>Library Requirements</title>
    <para>This ABI does not specify any additional interfaces for
    general-purpose libraries. However, certain processor-specific support
    routines are defined to ensure portability between ABI-conforming
    implementations.</para>
    <para>Such processor-specific support definitions concern vector and
    floating-point alignment, register save and restore routines, variable
    argument list layout, and a limited set of data definitions.</para>
    <section xml:id="dbdoclet.50655243___RefHeading___Toc377640666">
      <title>C Library Conformance with Generic ABI</title>
      <para />
      <section xml:id="dbdoclet.50655243___RefHeading___Toc377640667">
        <title>Malloc Routine Return Pointer Alignment</title>
        <para>The malloc( ) routine must always return a pointer with the
        alignment of the largest alignment needed for loads and stores of the
        built-in data types. This is currently 16 bytes.</para>
      </section>
      <section xml:id="dbdoclet.50655243___RefHeading___Toc377640668">
        <title>Library Handling of Limited-Access Bits in Registers</title>
        <para>Requirements for the handling of limited-access bits in certain
        registers by standard library functions are defined in 
        <xref linkend="dbdoclet.50655240___RefHeading___Toc377640581" />.</para>
      </section>
    </section>
    <section xml:id="dbdoclet.50655243_49403">
      <title>Save and Restore Routines</title>
      <para>All of the save and restore routines described in 
      <xref linkend="dbdoclet.50655240_24141" /> are required. These routines
      use unusual calling conventions due to their special purpose. Parameters
      for these functions are described in 
      <xref linkend="dbdoclet.50655240_41483" />, 
      <xref linkend="dbdoclet.50655240_56788" />, and 
      <xref linkend="dbdoclet.50655240_96790" />.</para>
      <para>The symbols for these functions shall be hidden and locally
      resolved within each module. The symbols so created shall not be
      exported.</para>
      <para>These functions can either be provided in a utility library that is
      linked by the linker to each module, or the functions can be synthesized
      by the linker as necessary to resolve symbols.</para>
    </section>
    <section xml:id="dbdoclet.50655243_page131">
      <title xml:id="dbdoclet.50655243___RefHeading___Toc377640670">Types Defined in the Standard Header</title>
      <para>The type va_list shall be defined as follows:</para>
      <para><literal>typedef void * va_list;</literal></para>
      <para>The following integer types are defined in headers, which must be
      provided by freestanding implementations, or have their limits defined in
      such headers. They shall have the following definitions:</para>
      <itemizedlist spacing="compact">
        <listitem>
          <para>typedef long ptrdiff_t;</para>
        </listitem>
        <listitem>
          <para>typedef unsigned <phrase>long</phrase> size_t;</para>
        </listitem>
        <listitem>
          <para>typedef <phrase>int</phrase> wchar_t;</para>
        </listitem>
        <listitem>
          <para>typedef int sig_atomic_t;</para>
        </listitem>
        <listitem>
          <para>typedef unsigned int wint_t;</para>
        </listitem>
        <listitem>
          <para>typedef signed char int8_t;</para>
        </listitem>
        <listitem>
          <para>typedef short int16_t;</para>
        </listitem>
        <listitem>
          <para>typedef int int32_t;</para>
        </listitem>
        <listitem>
          <para>typedef long int64_t;</para>
        </listitem>
        <listitem>
          <para>typedef unsigned char uint8_t;</para>
        </listitem>
        <listitem>
          <para>typedef unsigned short uint16_t;</para>
        </listitem>
        <listitem>
          <para>typedef unsigned int uint32_t;</para>
        </listitem>
        <listitem>
          <para>typedef unsigned long uint64_t;</para>
        </listitem>
        <listitem>
          <para>typedef signed char int_least8_t;</para>
        </listitem>
        <listitem>
          <para>typedef short int_least16_t;</para>
        </listitem>
        <listitem xml:id="dbdoclet.50655243_page136">
          <para>typedef int int_least32_t;</para>
        </listitem>
        <listitem>
          <para>typedef long int_least64_t;</para>
        </listitem>
        <listitem>
          <para>typedef unsigned char uint_least8_t;</para>
        </listitem>
        <listitem>
          <para>typedef unsigned short uint_least16_t;</para>
        </listitem>
        <listitem>
          <para>typedef unsigned int uint_least32_t;</para>
        </listitem>
        <listitem>
          <para>typedef unsigned long uint_least64_t;</para>
        </listitem>
        <listitem>
          <para>typedef signed char int_fast8_t;</para>
        </listitem>
        <listitem>
          <para>typedef int int_fast16_t;</para>
        </listitem>
        <listitem>
          <para>typedef int int_fast32_t;</para>
        </listitem>
        <listitem>
          <para>typedef long int_fast64_t;</para>
        </listitem>
        <listitem>
          <para>typedef unsigned char uint_fast8_t;</para>
        </listitem>
        <listitem>
          <para>typedef unsigned int uint_fast16_t;</para>
        </listitem>
        <listitem>
          <para>typedef unsigned int uint_fast32_t;</para>
        </listitem>
        <listitem>
          <para>typedef unsigned long uint_fast64_t;</para>
        </listitem>
        <listitem>
          <para>typedef long intptr_t;</para>
        </listitem>
        <listitem>
          <para>typedef unsigned long uintptr_t;</para>
        </listitem>
        <listitem>
          <para>typedef long intmax_t;</para>
        </listitem>
        <listitem>
          <para>typedef unsigned long uintmax_t;</para>
        </listitem>
      </itemizedlist>
    </section>
    <section xml:id="dbdoclet.50655243_75216">
      <title>Predefined Macros</title>
      <para>A C preprocessor that conforms to this ABI shall predefine the
      macro _CALL_ELF to have a value of 2.</para>
      <para>The macros listed in 
      <xref linkend="dbdoclet.50655243_37910" /> are based on environment
      characteristics. They shall be predefined to a value of 1 by conforming C
      preprocessors when the corresponding condition applies.</para>
      <para> </para>
      <table frame="all" pgwide="1" xml:id="dbdoclet.50655243_37910">
        <title>Predefined Target Architecture Macros</title>
        <tgroup cols="2">
          <colspec colname="c1" colwidth="20*" align="center"/>
          <colspec colname="c2" colwidth="80*" />
          <thead>
            <row>
              <entry>
                <para>
                  <emphasis role="bold">Macro</emphasis>
                </para>
              </entry>
              <entry align="center">
                <para>
                  <emphasis role="bold">Condition</emphasis>
                </para>
              </entry>
            </row>
          </thead>
          <tbody>
            <row>
              <entry>
                <para>__PPC__</para>
                <para>__powerpc__</para>
              </entry>
              <entry>
                <para>The target is a Power Architecture processor.</para>
              </entry>
            </row>
            <row>
              <entry>
                <para>__PPC64__</para>
                <para>__powerpc64__</para>
                <para>__64BIT__<footnote xml:id="pgfId-1101811">
                  <para>Phased in.</para>
                </footnote></para>
              </entry>
              <entry>
                <para>The target is a Power Architecture processor running in
                64-bit mode.</para>
              </entry>
            </row>
            <row>
              <entry>
                <para>__BIG_ENDIAN__</para>
              </entry>
              <entry>
                <para>The target processor is big endian.</para>
              </entry>
            </row>
            <row>
              <entry>
                <para>__LITTLE_ENDIAN__</para>
              </entry>
              <entry>
                <para>The target processor is little endian.</para>
              </entry>
            </row>
            <row>
              <entry>
                <para>_ARCH_PWRn</para>
              </entry>
              <entry>
                <para>Indicates that the target processor supports the Power
                ISA level for POWERn or higher. For example, _ARCH_PWR8 supports
                the Power ISA for a POWER8 processor.</para>
              </entry>
            </row>
          </tbody>
        </tgroup>
      </table>
      <para> </para>
      <para> </para>
      <para>The macros in listed 
      <xref linkend="dbdoclet.50655243_98814" /> are based on the order of the
      data elements. They shall be predefined to one of the allowable values by
      conforming C preprocessors when the corresponding condition
      applies.</para>
      <para> </para>
      <table frame="all" pgwide="1" xml:id="dbdoclet.50655243_98814">
        <title>Predefined Target Data Order Macros</title>
        <tgroup cols="3">
          <colspec colname="c1" colwidth="30*" align="center"/>
          <colspec colname="c2" colwidth="25*" align="center"/>
          <colspec colname="c3" colwidth="45*" />
          <thead>
            <row>
              <entry>
                <para>
                  <emphasis role="bold">Macro</emphasis>
                </para>
              </entry>
              <entry>
                <para>
                  <emphasis role="bold">Value</emphasis>
                </para>
              </entry>
              <entry align="center">
                <para>
                  <emphasis role="bold">Condition</emphasis>
                </para>
              </entry>
            </row>
          </thead>
          <tbody>
            <row>
              <entry morerows="1">
                <para>__BYTE_ORDER__</para>
              </entry>
              <entry>
                <para>__ORDER_BIG_ENDIAN__</para>
              </entry>
              <entry>
                <para>The target processor is big endian.</para>
              </entry>
            </row>
            <row>
              <entry>
                <para>__ORDER_LITTLE_ENDIAN__</para>
              </entry>
              <entry>
                <para>The target processor is little endian.</para>
              </entry>
            </row>
            <row>
              <entry morerows="1">
                <para>__FLOAT_WORD_ORDER__</para>
              </entry>
              <entry>
                <para>__ORDER_BIG_ENDIAN__</para>
              </entry>
              <entry>
                <para>The target processor is big endian.</para>
              </entry>
            </row>
            <row>
              <entry>
                <para>__ORDER_LITTLE_ENDIAN__</para>
              </entry>
              <entry>
                <para>The target processor is little endian.</para>
              </entry>
            </row>
            <row>
              <entry morerows="1">
                <para>__VEC_ELEMENT_REG_ORDER__</para>
                <para>For more information, see 
                <xref linkend="dbdoclet.50655244_25365" />.</para>
              </entry>
              <entry>
                <para>__ORDER_BIG_ENDIAN__</para>
              </entry>
              <entry>
                <para>The target processor is big endian, or big-endian vector
                element order has been requested.</para>
              </entry>
            </row>
            <row>
              <entry>
                <para>__ORDER_LITTLE_ENDIAN__</para>
              </entry>
              <entry>
                <para>The target processor is little endian, and big-endian
                vector element order has not been requested.</para>
              </entry>
            </row>
          </tbody>
        </tgroup>
      </table>
      <para> </para>
      <para> </para>
    </section>
  </section>
  <section>
    <title>POWER ISA-Specific API and ABI Extensions</title>
    <para>The Data Stream Control Register (DSCR) affects how the processor
    handles data streams that are detected by the hardware and defined by the
    software. For more information, see “Data Stream Control Overview, ABI, and
    API” at the following link:</para>
    <para><link xl:href="https://github.com/paflib/paflib/wiki/Data-Stream-Control-Overview,-ABI,-and-API">https://github.com/paflib/paflib/wiki/Data-Stream-Control-Overview,-ABI,-and-API</link>
    </para>
    <para>The event-based branching facility generates exceptions when certain
    criteria are met. For more information, see the “Event Based Branching
    Overview, ABI, and API” section at the following link:</para>
    <para><link xl:href="https://github.com/paflib/paflib/wiki/Event-Based-Branching----Overview,-ABI,-and-API">https://github.com/paflib/paflib/wiki/Event-Based-Branching----Overview,-ABI,-and-API</link>
    </para>
  </section>
</chapter>