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| <title>GNU Compiler Collection (GCC) Internals: Integer library routines</title> |
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| <a name="Integer-library-routines"></a> |
| <div class="header"> |
| <p> |
| Next: <a href="Soft-float-library-routines.html#Soft-float-library-routines" accesskey="n" rel="next">Soft float library routines</a>, Up: <a href="Libgcc.html#Libgcc" accesskey="u" rel="up">Libgcc</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p> |
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| <a name="Routines-for-integer-arithmetic"></a> |
| <h3 class="section">4.1 Routines for integer arithmetic</h3> |
| |
| <p>The integer arithmetic routines are used on platforms that don’t provide |
| hardware support for arithmetic operations on some modes. |
| </p> |
| <a name="Arithmetic-functions"></a> |
| <h4 class="subsection">4.1.1 Arithmetic functions</h4> |
| |
| <dl> |
| <dt><a name="index-_005f_005fashlsi3"></a>Runtime Function: <em>int</em> <strong>__ashlsi3</strong> <em>(int <var>a</var>, int <var>b</var>)</em></dt> |
| <dt><a name="index-_005f_005fashldi3"></a>Runtime Function: <em>long</em> <strong>__ashldi3</strong> <em>(long <var>a</var>, int <var>b</var>)</em></dt> |
| <dt><a name="index-_005f_005fashlti3"></a>Runtime Function: <em>long long</em> <strong>__ashlti3</strong> <em>(long long <var>a</var>, int <var>b</var>)</em></dt> |
| <dd><p>These functions return the result of shifting <var>a</var> left by <var>b</var> bits. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-_005f_005fashrsi3"></a>Runtime Function: <em>int</em> <strong>__ashrsi3</strong> <em>(int <var>a</var>, int <var>b</var>)</em></dt> |
| <dt><a name="index-_005f_005fashrdi3"></a>Runtime Function: <em>long</em> <strong>__ashrdi3</strong> <em>(long <var>a</var>, int <var>b</var>)</em></dt> |
| <dt><a name="index-_005f_005fashrti3"></a>Runtime Function: <em>long long</em> <strong>__ashrti3</strong> <em>(long long <var>a</var>, int <var>b</var>)</em></dt> |
| <dd><p>These functions return the result of arithmetically shifting <var>a</var> right |
| by <var>b</var> bits. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-_005f_005fdivsi3"></a>Runtime Function: <em>int</em> <strong>__divsi3</strong> <em>(int <var>a</var>, int <var>b</var>)</em></dt> |
| <dt><a name="index-_005f_005fdivdi3"></a>Runtime Function: <em>long</em> <strong>__divdi3</strong> <em>(long <var>a</var>, long <var>b</var>)</em></dt> |
| <dt><a name="index-_005f_005fdivti3"></a>Runtime Function: <em>long long</em> <strong>__divti3</strong> <em>(long long <var>a</var>, long long <var>b</var>)</em></dt> |
| <dd><p>These functions return the quotient of the signed division of <var>a</var> and |
| <var>b</var>. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-_005f_005flshrsi3"></a>Runtime Function: <em>int</em> <strong>__lshrsi3</strong> <em>(int <var>a</var>, int <var>b</var>)</em></dt> |
| <dt><a name="index-_005f_005flshrdi3"></a>Runtime Function: <em>long</em> <strong>__lshrdi3</strong> <em>(long <var>a</var>, int <var>b</var>)</em></dt> |
| <dt><a name="index-_005f_005flshrti3"></a>Runtime Function: <em>long long</em> <strong>__lshrti3</strong> <em>(long long <var>a</var>, int <var>b</var>)</em></dt> |
| <dd><p>These functions return the result of logically shifting <var>a</var> right by |
| <var>b</var> bits. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-_005f_005fmodsi3"></a>Runtime Function: <em>int</em> <strong>__modsi3</strong> <em>(int <var>a</var>, int <var>b</var>)</em></dt> |
| <dt><a name="index-_005f_005fmoddi3"></a>Runtime Function: <em>long</em> <strong>__moddi3</strong> <em>(long <var>a</var>, long <var>b</var>)</em></dt> |
| <dt><a name="index-_005f_005fmodti3"></a>Runtime Function: <em>long long</em> <strong>__modti3</strong> <em>(long long <var>a</var>, long long <var>b</var>)</em></dt> |
| <dd><p>These functions return the remainder of the signed division of <var>a</var> |
| and <var>b</var>. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-_005f_005fmulsi3"></a>Runtime Function: <em>int</em> <strong>__mulsi3</strong> <em>(int <var>a</var>, int <var>b</var>)</em></dt> |
| <dt><a name="index-_005f_005fmuldi3"></a>Runtime Function: <em>long</em> <strong>__muldi3</strong> <em>(long <var>a</var>, long <var>b</var>)</em></dt> |
| <dt><a name="index-_005f_005fmulti3"></a>Runtime Function: <em>long long</em> <strong>__multi3</strong> <em>(long long <var>a</var>, long long <var>b</var>)</em></dt> |
| <dd><p>These functions return the product of <var>a</var> and <var>b</var>. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-_005f_005fnegdi2"></a>Runtime Function: <em>long</em> <strong>__negdi2</strong> <em>(long <var>a</var>)</em></dt> |
| <dt><a name="index-_005f_005fnegti2"></a>Runtime Function: <em>long long</em> <strong>__negti2</strong> <em>(long long <var>a</var>)</em></dt> |
| <dd><p>These functions return the negation of <var>a</var>. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-_005f_005fudivsi3"></a>Runtime Function: <em>unsigned int</em> <strong>__udivsi3</strong> <em>(unsigned int <var>a</var>, unsigned int <var>b</var>)</em></dt> |
| <dt><a name="index-_005f_005fudivdi3"></a>Runtime Function: <em>unsigned long</em> <strong>__udivdi3</strong> <em>(unsigned long <var>a</var>, unsigned long <var>b</var>)</em></dt> |
| <dt><a name="index-_005f_005fudivti3"></a>Runtime Function: <em>unsigned long long</em> <strong>__udivti3</strong> <em>(unsigned long long <var>a</var>, unsigned long long <var>b</var>)</em></dt> |
| <dd><p>These functions return the quotient of the unsigned division of <var>a</var> |
| and <var>b</var>. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-_005f_005fudivmoddi4"></a>Runtime Function: <em>unsigned long</em> <strong>__udivmoddi4</strong> <em>(unsigned long <var>a</var>, unsigned long <var>b</var>, unsigned long *<var>c</var>)</em></dt> |
| <dt><a name="index-_005f_005fudivmodti4"></a>Runtime Function: <em>unsigned long long</em> <strong>__udivmodti4</strong> <em>(unsigned long long <var>a</var>, unsigned long long <var>b</var>, unsigned long long *<var>c</var>)</em></dt> |
| <dd><p>These functions calculate both the quotient and remainder of the unsigned |
| division of <var>a</var> and <var>b</var>. The return value is the quotient, and |
| the remainder is placed in variable pointed to by <var>c</var>. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-_005f_005fumodsi3"></a>Runtime Function: <em>unsigned int</em> <strong>__umodsi3</strong> <em>(unsigned int <var>a</var>, unsigned int <var>b</var>)</em></dt> |
| <dt><a name="index-_005f_005fumoddi3"></a>Runtime Function: <em>unsigned long</em> <strong>__umoddi3</strong> <em>(unsigned long <var>a</var>, unsigned long <var>b</var>)</em></dt> |
| <dt><a name="index-_005f_005fumodti3"></a>Runtime Function: <em>unsigned long long</em> <strong>__umodti3</strong> <em>(unsigned long long <var>a</var>, unsigned long long <var>b</var>)</em></dt> |
| <dd><p>These functions return the remainder of the unsigned division of <var>a</var> |
| and <var>b</var>. |
| </p></dd></dl> |
| |
| <a name="Comparison-functions"></a> |
| <h4 class="subsection">4.1.2 Comparison functions</h4> |
| |
| <p>The following functions implement integral comparisons. These functions |
| implement a low-level compare, upon which the higher level comparison |
| operators (such as less than and greater than or equal to) can be |
| constructed. The returned values lie in the range zero to two, to allow |
| the high-level operators to be implemented by testing the returned |
| result using either signed or unsigned comparison. |
| </p> |
| <dl> |
| <dt><a name="index-_005f_005fcmpdi2"></a>Runtime Function: <em>int</em> <strong>__cmpdi2</strong> <em>(long <var>a</var>, long <var>b</var>)</em></dt> |
| <dt><a name="index-_005f_005fcmpti2"></a>Runtime Function: <em>int</em> <strong>__cmpti2</strong> <em>(long long <var>a</var>, long long <var>b</var>)</em></dt> |
| <dd><p>These functions perform a signed comparison of <var>a</var> and <var>b</var>. If |
| <var>a</var> is less than <var>b</var>, they return 0; if <var>a</var> is greater than |
| <var>b</var>, they return 2; and if <var>a</var> and <var>b</var> are equal they return 1. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-_005f_005fucmpdi2"></a>Runtime Function: <em>int</em> <strong>__ucmpdi2</strong> <em>(unsigned long <var>a</var>, unsigned long <var>b</var>)</em></dt> |
| <dt><a name="index-_005f_005fucmpti2"></a>Runtime Function: <em>int</em> <strong>__ucmpti2</strong> <em>(unsigned long long <var>a</var>, unsigned long long <var>b</var>)</em></dt> |
| <dd><p>These functions perform an unsigned comparison of <var>a</var> and <var>b</var>. |
| If <var>a</var> is less than <var>b</var>, they return 0; if <var>a</var> is greater than |
| <var>b</var>, they return 2; and if <var>a</var> and <var>b</var> are equal they return 1. |
| </p></dd></dl> |
| |
| <a name="Trapping-arithmetic-functions"></a> |
| <h4 class="subsection">4.1.3 Trapping arithmetic functions</h4> |
| |
| <p>The following functions implement trapping arithmetic. These functions |
| call the libc function <code>abort</code> upon signed arithmetic overflow. |
| </p> |
| <dl> |
| <dt><a name="index-_005f_005fabsvsi2"></a>Runtime Function: <em>int</em> <strong>__absvsi2</strong> <em>(int <var>a</var>)</em></dt> |
| <dt><a name="index-_005f_005fabsvdi2"></a>Runtime Function: <em>long</em> <strong>__absvdi2</strong> <em>(long <var>a</var>)</em></dt> |
| <dd><p>These functions return the absolute value of <var>a</var>. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-_005f_005faddvsi3"></a>Runtime Function: <em>int</em> <strong>__addvsi3</strong> <em>(int <var>a</var>, int <var>b</var>)</em></dt> |
| <dt><a name="index-_005f_005faddvdi3"></a>Runtime Function: <em>long</em> <strong>__addvdi3</strong> <em>(long <var>a</var>, long <var>b</var>)</em></dt> |
| <dd><p>These functions return the sum of <var>a</var> and <var>b</var>; that is |
| <code><var>a</var> + <var>b</var></code>. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-_005f_005fmulvsi3"></a>Runtime Function: <em>int</em> <strong>__mulvsi3</strong> <em>(int <var>a</var>, int <var>b</var>)</em></dt> |
| <dt><a name="index-_005f_005fmulvdi3"></a>Runtime Function: <em>long</em> <strong>__mulvdi3</strong> <em>(long <var>a</var>, long <var>b</var>)</em></dt> |
| <dd><p>The functions return the product of <var>a</var> and <var>b</var>; that is |
| <code><var>a</var> * <var>b</var></code>. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-_005f_005fnegvsi2"></a>Runtime Function: <em>int</em> <strong>__negvsi2</strong> <em>(int <var>a</var>)</em></dt> |
| <dt><a name="index-_005f_005fnegvdi2"></a>Runtime Function: <em>long</em> <strong>__negvdi2</strong> <em>(long <var>a</var>)</em></dt> |
| <dd><p>These functions return the negation of <var>a</var>; that is <code>-<var>a</var></code>. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-_005f_005fsubvsi3"></a>Runtime Function: <em>int</em> <strong>__subvsi3</strong> <em>(int <var>a</var>, int <var>b</var>)</em></dt> |
| <dt><a name="index-_005f_005fsubvdi3"></a>Runtime Function: <em>long</em> <strong>__subvdi3</strong> <em>(long <var>a</var>, long <var>b</var>)</em></dt> |
| <dd><p>These functions return the difference between <var>b</var> and <var>a</var>; |
| that is <code><var>a</var> - <var>b</var></code>. |
| </p></dd></dl> |
| |
| <a name="Bit-operations"></a> |
| <h4 class="subsection">4.1.4 Bit operations</h4> |
| |
| <dl> |
| <dt><a name="index-_005f_005fclzsi2"></a>Runtime Function: <em>int</em> <strong>__clzsi2</strong> <em>(int <var>a</var>)</em></dt> |
| <dt><a name="index-_005f_005fclzdi2"></a>Runtime Function: <em>int</em> <strong>__clzdi2</strong> <em>(long <var>a</var>)</em></dt> |
| <dt><a name="index-_005f_005fclzti2"></a>Runtime Function: <em>int</em> <strong>__clzti2</strong> <em>(long long <var>a</var>)</em></dt> |
| <dd><p>These functions return the number of leading 0-bits in <var>a</var>, starting |
| at the most significant bit position. If <var>a</var> is zero, the result is |
| undefined. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-_005f_005fctzsi2"></a>Runtime Function: <em>int</em> <strong>__ctzsi2</strong> <em>(int <var>a</var>)</em></dt> |
| <dt><a name="index-_005f_005fctzdi2"></a>Runtime Function: <em>int</em> <strong>__ctzdi2</strong> <em>(long <var>a</var>)</em></dt> |
| <dt><a name="index-_005f_005fctzti2"></a>Runtime Function: <em>int</em> <strong>__ctzti2</strong> <em>(long long <var>a</var>)</em></dt> |
| <dd><p>These functions return the number of trailing 0-bits in <var>a</var>, starting |
| at the least significant bit position. If <var>a</var> is zero, the result is |
| undefined. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-_005f_005fffsdi2"></a>Runtime Function: <em>int</em> <strong>__ffsdi2</strong> <em>(long <var>a</var>)</em></dt> |
| <dt><a name="index-_005f_005fffsti2"></a>Runtime Function: <em>int</em> <strong>__ffsti2</strong> <em>(long long <var>a</var>)</em></dt> |
| <dd><p>These functions return the index of the least significant 1-bit in <var>a</var>, |
| or the value zero if <var>a</var> is zero. The least significant bit is index |
| one. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-_005f_005fparitysi2"></a>Runtime Function: <em>int</em> <strong>__paritysi2</strong> <em>(int <var>a</var>)</em></dt> |
| <dt><a name="index-_005f_005fparitydi2"></a>Runtime Function: <em>int</em> <strong>__paritydi2</strong> <em>(long <var>a</var>)</em></dt> |
| <dt><a name="index-_005f_005fparityti2"></a>Runtime Function: <em>int</em> <strong>__parityti2</strong> <em>(long long <var>a</var>)</em></dt> |
| <dd><p>These functions return the value zero if the number of bits set in |
| <var>a</var> is even, and the value one otherwise. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-_005f_005fpopcountsi2"></a>Runtime Function: <em>int</em> <strong>__popcountsi2</strong> <em>(int <var>a</var>)</em></dt> |
| <dt><a name="index-_005f_005fpopcountdi2"></a>Runtime Function: <em>int</em> <strong>__popcountdi2</strong> <em>(long <var>a</var>)</em></dt> |
| <dt><a name="index-_005f_005fpopcountti2"></a>Runtime Function: <em>int</em> <strong>__popcountti2</strong> <em>(long long <var>a</var>)</em></dt> |
| <dd><p>These functions return the number of bits set in <var>a</var>. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-_005f_005fbswapsi2"></a>Runtime Function: <em>int32_t</em> <strong>__bswapsi2</strong> <em>(int32_t <var>a</var>)</em></dt> |
| <dt><a name="index-_005f_005fbswapdi2"></a>Runtime Function: <em>int64_t</em> <strong>__bswapdi2</strong> <em>(int64_t <var>a</var>)</em></dt> |
| <dd><p>These functions return the <var>a</var> byteswapped. |
| </p></dd></dl> |
| |
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