From 990090a4cc9070837d31e66b58d40f0c3d038741 Mon Sep 17 00:00:00 2001 From: Yuval Adam Date: Sun, 16 Mar 2014 14:41:11 +0200 Subject: Add usblib and utils --- utils/isqrt.c | 118 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 118 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..aa908f6 --- /dev/null +++ b/utils/isqrt.c @@ -0,0 +1,118 @@ +//***************************************************************************** +// +// isqrt.c - Integer square root. +// +// Copyright (c) 2005-2014 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 2.1.0.12573 of the Tiva Utility Library. +// +//***************************************************************************** + +#include +#include "utils/isqrt.h" + +//***************************************************************************** +// +//! \addtogroup isqrt_api +//! @{ +// +//***************************************************************************** + +//***************************************************************************** +// +//! Compute the integer square root of an integer. +//! +//! \param ui32Value 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. +// +//***************************************************************************** +uint32_t +isqrt(uint32_t ui32Value) +{ + uint32_t ui32Rem, ui32Root, ui32Idx; + + // + // Initialize the remainder and root to zero. + // + ui32Rem = 0; + ui32Root = 0; + + // + // Loop over the sixteen bits in the root. + // + for(ui32Idx = 0; ui32Idx < 16; ui32Idx++) + { + // + // Shift the root up by a bit to make room for the new bit that is + // about to be computed. + // + ui32Root <<= 1; + + // + // Get two more bits from the input into the remainder. + // + ui32Rem = ((ui32Rem << 2) + (ui32Value >> 30)); + ui32Value <<= 2; + + // + // Make the test root be 2n + 1. + // + ui32Root++; + + // + // See if the root is greater than the remainder. + // + if(ui32Root <= ui32Rem) + { + // + // Subtract the test root from the remainder. + // + ui32Rem -= ui32Root; + + // + // Increment the root, setting the second LSB. + // + ui32Root++; + } + else + { + // + // The root is greater than the remainder, so the new bit of the + // root is actually zero. + // + ui32Root--; + } + } + + // + // Return the computed root. + // + return(ui32Root >> 1); +} + +//***************************************************************************** +// +// Close the Doxygen group. +//! @} +// +//***************************************************************************** -- cgit v1.3.1