arithmetic.c File Reference

#include <stdint.h>

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Functions
static uint32_t	divl (uint64_t n, uint32_t d)
	On x86, division of one 64-bit integer by another cannot be done with a single instruction or a short sequence. More...
static int	nlz (uint32_t x)
	Returns the number of leading zero bits in X, which must be nonzero. More...
static uint64_t	udiv64 (uint64_t n, uint64_t d)
	Divides unsigned 64-bit N by unsigned 64-bit D and returns the quotient. More...
static uint32_t	umod64 (uint64_t n, uint64_t d)
	Divides unsigned 64-bit N by unsigned 64-bit D and returns the remainder. More...
static int64_t	sdiv64 (int64_t n, int64_t d)
	Divides signed 64-bit N by signed 64-bit D and returns the quotient. More...
static int32_t	smod64 (int64_t n, int64_t d)
	Divides signed 64-bit N by signed 64-bit D and returns the remainder. More...
long long	__divdi3 (long long n, long long d)
	These are the routines that GCC calls. More...
long long	__moddi3 (long long n, long long d)
	Signed 64-bit remainder. More...
unsigned long long	__udivdi3 (unsigned long long n, unsigned long long d)
	Unsigned 64-bit division. More...
unsigned long long	__umoddi3 (unsigned long long n, unsigned long long d)
	Unsigned 64-bit remainder. More...

Function Documentation

__divdi3()

long long __divdi3	(	long long	n,
		long long	d
	)

These are the routines that GCC calls.

Signed 64-bit division.

Definition at line 165 of file arithmetic.c.

References sdiv64().

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__moddi3()

long long __moddi3	(	long long	n,
		long long	d
	)

Signed 64-bit remainder.

Definition at line 172 of file arithmetic.c.

References smod64().

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__udivdi3()

unsigned long long __udivdi3	(	unsigned long long	n,
		unsigned long long	d
	)

Unsigned 64-bit division.

Definition at line 179 of file arithmetic.c.

References udiv64().

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__umoddi3()

unsigned long long __umoddi3	(	unsigned long long	n,
		unsigned long long	d
	)

Unsigned 64-bit remainder.

Definition at line 186 of file arithmetic.c.

References umod64().

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divl()

static uint32_t divl ( uint64_t  n, uint32_t  d  )

inlinestatic

On x86, division of one 64-bit integer by another cannot be done with a single instruction or a short sequence.

Thus, GCC implements 64-bit division and remainder operations through function calls. These functions are normally obtained from libgcc, which is automatically included by GCC in any link that it does.

Some x86-64 machines, however, have a compiler and utilities that can generate 32-bit x86 code without having any of the necessary libraries, including libgcc. Thus, we can make Pintos work on these machines by simply implementing our own 64-bit division routines, which are the only routines from libgcc that Pintos requires.

Completeness is another reason to include these routines. If Pintos is completely self-contained, then that makes it that much less mysterious. Uses x86 DIVL instruction to divide 64-bit N by 32-bit D to yield a 32-bit quotient. Returns the quotient. Traps with a divide error (#DE) if the quotient does not fit in 32 bits.

Definition at line 26 of file arithmetic.c.

Referenced by udiv64().

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nlz()

static int nlz ( uint32_t  x )

static

Returns the number of leading zero bits in X, which must be nonzero.

Definition at line 42 of file arithmetic.c.

References x.

Referenced by udiv64().

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sdiv64()

static int64_t sdiv64 ( int64_t  n, int64_t  d  )

static

Divides signed 64-bit N by signed 64-bit D and returns the quotient.

Definition at line 140 of file arithmetic.c.

References udiv64().

Referenced by __divdi3(), and smod64().

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smod64()

static int32_t smod64 ( int64_t  n, int64_t  d  )

static

Divides signed 64-bit N by signed 64-bit D and returns the remainder.

Definition at line 151 of file arithmetic.c.

References sdiv64().

Referenced by __moddi3().

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udiv64()

static uint64_t udiv64 ( uint64_t  n, uint64_t  d  )

static

Divides unsigned 64-bit N by unsigned 64-bit D and returns the quotient.

Definition at line 78 of file arithmetic.c.

References divl(), nlz(), and s.

Referenced by __udivdi3(), sdiv64(), and umod64().

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umod64()

static uint32_t umod64 ( uint64_t  n, uint64_t  d  )

static

Divides unsigned 64-bit N by unsigned 64-bit D and returns the remainder.

Definition at line 132 of file arithmetic.c.

References udiv64().

Referenced by __umoddi3().

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