From 4ba8614c006f9828f0796c140bc3e13c9e67938c Mon Sep 17 00:00:00 2001 From: Yuval Adam Date: Mon, 29 Oct 2012 23:06:01 +0200 Subject: Added utils --- utils/isqrt.c | 117 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 117 insertions(+) create mode 100644 utils/isqrt.c (limited to 'utils/isqrt.c') diff --git a/utils/isqrt.c b/utils/isqrt.c new file mode 100644 index 0000000..d347e1e --- /dev/null +++ b/utils/isqrt.c @@ -0,0 +1,117 @@ +//***************************************************************************** +// +// isqrt.c - Integer square root. +// +// Copyright (c) 2005-2012 Texas Instruments Incorporated. All rights reserved. +// Software License Agreement +// +// Texas Instruments (TI) is supplying this software for use solely and +// exclusively on TI's microcontroller products. The software is owned by +// TI and/or its suppliers, and is protected under applicable copyright +// laws. You may not combine this software with "viral" open-source +// software in order to form a larger program. +// +// THIS SOFTWARE IS PROVIDED "AS IS" AND WITH ALL FAULTS. +// NO WARRANTIES, WHETHER EXPRESS, IMPLIED OR STATUTORY, INCLUDING, BUT +// NOT LIMITED TO, IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE APPLY TO THIS SOFTWARE. TI SHALL NOT, UNDER ANY +// CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL, OR CONSEQUENTIAL +// DAMAGES, FOR ANY REASON WHATSOEVER. +// +// This is part of revision 9453 of the Stellaris Firmware Development Package. +// +//***************************************************************************** + +#include "utils/isqrt.h" + +//***************************************************************************** +// +//! \addtogroup isqrt_api +//! @{ +// +//***************************************************************************** + +//***************************************************************************** +// +//! Compute the integer square root of an integer. +//! +//! \param ulValue is the value whose square root is desired. +//! +//! This function will compute the integer square root of the given input +//! value. Since the value returned is also an integer, it is actually better +//! defined as the largest integer whose square is less than or equal to the +//! input value. +//! +//! \return Returns the square root of the input value. +// +//***************************************************************************** +unsigned long +isqrt(unsigned long ulValue) +{ + unsigned long ulRem, ulRoot, ulIdx; + + // + // Initialize the remainder and root to zero. + // + ulRem = 0; + ulRoot = 0; + + // + // Loop over the sixteen bits in the root. + // + for(ulIdx = 0; ulIdx < 16; ulIdx++) + { + // + // Shift the root up by a bit to make room for the new bit that is + // about to be computed. + // + ulRoot <<= 1; + + // + // Get two more bits from the input into the remainder. + // + ulRem = ((ulRem << 2) + (ulValue >> 30)); + ulValue <<= 2; + + // + // Make the test root be 2n + 1. + // + ulRoot++; + + // + // See if the root is greater than the remainder. + // + if(ulRoot <= ulRem) + { + // + // Subtract the test root from the remainder. + // + ulRem -= ulRoot; + + // + // Increment the root, setting the second LSB. + // + ulRoot++; + } + else + { + // + // The root is greater than the remainder, so the new bit of the + // root is actually zero. + // + ulRoot--; + } + } + + // + // Return the computed root. + // + return(ulRoot >> 1); +} + +//***************************************************************************** +// +// Close the Doxygen group. +//! @} +// +//***************************************************************************** -- cgit v1.3.1