cgul_multiply64.h File Reference

portable multiplication that can produce 64-bit products More...

#include "cgul_common.h"
#include "cgul_exception.h"

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Functions
CGUL_BEGIN_C CGUL_EXPORT void	cgul_multiply64 (cgul_exception_t *cex, unsigned int x, unsigned int y, unsigned int *high, unsigned int *low)

Detailed Description

Portable multiplication that can produce 64-bit products.

Author

Paul Serice

Function Documentation

cgul_multiply64()

CGUL_BEGIN_C CGUL_EXPORT void cgul_multiply64	(	cgul_exception_t *	cex,
		unsigned int	x,
		unsigned int	y,
		unsigned int *	high,
		unsigned int *	low
	)

This function multiplies two 32-bit unsigned integers x and y to produce a 64-bit unsigned product using only 32-bit arithmetic. The high 32-bits of the 64-bit product will be stored in *high if high is not NULL, and the low 32-bits of the 64-bit product will be stored in *low if low is not NULL.

The following printf() format specification can be used to convert *high and *low into a proper hexadecimal string because it accounts for the significance of the leading zeros in *low:

    printf("%#0x%08x", *high, *low);

This function takes about 2.5 times as long to run as native 64-bit multiplication. Thus, it should only be used if your compiler does not support a 64-bit type. To conditionally use this code, include the "cgul_int.h" header and test if CGUL_UINT64 is not defined.

Parameters

[in]	cex	c-style exception
[in]	x	first 32-bit multiplicand
[in]	y	second 32-bit multiplicand
[out]	high	high 32-bits of the product of x and y
[out]	low	low 32-bits of the product of x and y

Referenced by cgul_multiply64_cxx::multiply64().