diff options
| author | Yuval Adam <yuv.adm@gmail.com> | 2012-10-29 23:06:01 +0200 |
|---|---|---|
| committer | Yuval Adam <yuv.adm@gmail.com> | 2012-10-29 23:06:01 +0200 |
| commit | 4ba8614c006f9828f0796c140bc3e13c9e67938c (patch) | |
| tree | ad204651c733250d27d20fce8820f9747c43c883 /utils/isqrt.c | |
| parent | e018ceebed74b8223482bc9d1ed0b31c938381da (diff) | |
Added utils
Diffstat (limited to 'utils/isqrt.c')
| -rw-r--r-- | utils/isqrt.c | 117 |
1 files changed, 117 insertions, 0 deletions
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.
+//! @}
+//
+//*****************************************************************************
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