The integer arithmetic routines are used on platforms that don’t provide hardware support for arithmetic operations on some modes.
int __ashlsi3 (int a, int b) ¶long __ashldi3 (long a, int b) ¶long long __ashlti3 (long long a, int b) ¶These functions return the result of shifting a left by b bits.
int __ashrsi3 (int a, int b) ¶long __ashrdi3 (long a, int b) ¶long long __ashrti3 (long long a, int b) ¶These functions return the result of arithmetically shifting a right by b bits.
int __divsi3 (int a, int b) ¶long __divdi3 (long a, long b) ¶long long __divti3 (long long a, long long b) ¶These functions return the quotient of the signed division of a and b.
int __lshrsi3 (int a, int b) ¶long __lshrdi3 (long a, int b) ¶long long __lshrti3 (long long a, int b) ¶These functions return the result of logically shifting a right by b bits.
int __modsi3 (int a, int b) ¶long __moddi3 (long a, long b) ¶long long __modti3 (long long a, long long b) ¶These functions return the remainder of the signed division of a and b.
int __mulsi3 (int a, int b) ¶long __muldi3 (long a, long b) ¶long long __multi3 (long long a, long long b) ¶These functions return the product of a and b.
long __negdi2 (long a) ¶long long __negti2 (long long a) ¶These functions return the negation of a.
unsigned int __udivsi3 (unsigned int a, unsigned int b) ¶unsigned long __udivdi3 (unsigned long a, unsigned long b) ¶unsigned long long __udivti3 (unsigned long long a, unsigned long long b) ¶These functions return the quotient of the unsigned division of a and b.
unsigned long __udivmoddi4 (unsigned long a, unsigned long b, unsigned long *c) ¶unsigned long long __udivmodti4 (unsigned long long a, unsigned long long b, unsigned long long *c) ¶These functions calculate both the quotient and remainder of the unsigned division of a and b. The return value is the quotient, and the remainder is placed in variable pointed to by c.
unsigned int __umodsi3 (unsigned int a, unsigned int b) ¶unsigned long __umoddi3 (unsigned long a, unsigned long b) ¶unsigned long long __umodti3 (unsigned long long a, unsigned long long b) ¶These functions return the remainder of the unsigned division of a and b.
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.
int __cmpdi2 (long a, long b) ¶int __cmpti2 (long long a, long long b) ¶These functions perform a signed comparison of a and b. If a is less than b, they return 0; if a is greater than b, they return 2; and if a and b are equal they return 1.
int __ucmpdi2 (unsigned long a, unsigned long b) ¶int __ucmpti2 (unsigned long long a, unsigned long long b) ¶These functions perform an unsigned comparison of a and b. If a is less than b, they return 0; if a is greater than b, they return 2; and if a and b are equal they return 1.
The following functions implement trapping arithmetic. These functions
call the libc function abort upon signed arithmetic overflow.
int __absvsi2 (int a) ¶long __absvdi2 (long a) ¶These functions return the absolute value of a.
int __addvsi3 (int a, int b) ¶long __addvdi3 (long a, long b) ¶These functions return the sum of a and b; that is
a + b.
int __mulvsi3 (int a, int b) ¶long __mulvdi3 (long a, long b) ¶The functions return the product of a and b; that is
a * b.
int __clzsi2 (unsigned int a) ¶int __clzdi2 (unsigned long a) ¶int __clzti2 (unsigned long long a) ¶These functions return the number of leading 0-bits in a, starting at the most significant bit position. If a is zero, the result is undefined.
int __ctzsi2 (unsigned int a) ¶int __ctzdi2 (unsigned long a) ¶int __ctzti2 (unsigned long long a) ¶These functions return the number of trailing 0-bits in a, starting at the least significant bit position. If a is zero, the result is undefined.
int __ffsdi2 (unsigned long a) ¶int __ffsti2 (unsigned long long a) ¶These functions return the index of the least significant 1-bit in a, or the value zero if a is zero. The least significant bit is index one.
int __paritysi2 (unsigned int a) ¶int __paritydi2 (unsigned long a) ¶int __parityti2 (unsigned long long a) ¶These functions return the value zero if the number of bits set in a is even, and the value one otherwise.
_BitInt(n) library functions operate on arrays of limbs, where
each limb has __LIBGCC_BITINT_LIMB_WIDTH__ bits and the limbs are
ordered according to __LIBGCC_BITINT_ORDER__ ordering. The most
significant limb if n is not divisible by
__LIBGCC_BITINT_LIMB_WIDTH__ contains padding bits which should be
ignored on read (sign or zero extended), but extended on write. For the
library functions, all bit-precise integers regardless of n are
represented like that, even when the target ABI says that for some small
n they should be represented differently in memory. A pointer
to the array of limbs argument is always accompanied with a bit size
argument. If that argument is positive, it is number of bits and the
number is assumed to be zero-extended to infinite precision, if that
argument is negative, it is negated number of bits above which all bits
are assumed to be sign-extended to infinite precision. These number of bits
arguments don’t need to match actual n for the operation used in the
source, they could be lowered because of sign or zero extensions on the
input or because value-range optimization figures value will need certain
lower number of bits. For big-endian ordering of limbs, when lowering
the bit size argument the pointer argument needs to be adjusted as well.
Negative bit size argument should be always smaller or equal to -2,
because signed _BitInt(1) is not valid.
For output arguments, either the corresponding bit size argument should
be always positive (for multiplication and division), or is negative when
the output of conversion from floating-point value is signed and positive
when unsigned. The arrays of limbs output arguments point to should not
overlap any inputs, while input arrays of limbs can overlap.
UBILtype below stands for unsigned integer type with
__LIBGCC_BITINT_LIMB_WIDTH__ bit precision.
void __mulbitint3 (UBILtype *ret, int32_t retprec, const UBILtype *u, int32_t uprec, const UBILtype *v, int32_t vprec) ¶This function multiplies bit-precise integer operands u and v and stores result into retprec precision bit-precise integer result ret.
void __divmodbitint4 (UBILtype *q, int32_t qprec, UBILtype *r, int32_t rprec, const UBILtype *u, int32_t uprec, const UBILtype *v, int32_t vprec) ¶This function divides bit-precise integer operands u and v and stores
quotient into qprec precision bit-precise integer result q
(unless q is NULL and qprec is 0, in that case quotient
is not stored anywhere) and remainder into rprec precision bit-precise
integer result r (similarly, unless r is NULL and rprec
is 0).