diff options
| author | Yuval Adam <yuv.adm@gmail.com> | 2014-06-29 12:34:32 +0300 |
|---|---|---|
| committer | Yuval Adam <yuv.adm@gmail.com> | 2014-06-29 12:34:32 +0300 |
| commit | c3e4c9a25c2910d2d66d52215b3406b13d5b23d5 (patch) | |
| tree | added370d1e356901f8579f076e3263fb0464db7 /boards/dk-tm4c129x/freertos_demo/random.c | |
| parent | 990090a4cc9070837d31e66b58d40f0c3d038741 (diff) | |
Add more board models
Diffstat (limited to 'boards/dk-tm4c129x/freertos_demo/random.c')
| -rw-r--r-- | boards/dk-tm4c129x/freertos_demo/random.c | 176 |
1 files changed, 176 insertions, 0 deletions
diff --git a/boards/dk-tm4c129x/freertos_demo/random.c b/boards/dk-tm4c129x/freertos_demo/random.c new file mode 100644 index 0000000..6918a8f --- /dev/null +++ b/boards/dk-tm4c129x/freertos_demo/random.c @@ -0,0 +1,176 @@ +//*****************************************************************************
+//
+// random.c - Random number generator utilizing MD4 hash function of
+// environmental noise captured as the seed and a linear congruence
+// generator for the random numbers.
+//
+// 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 DK-TM4C129X Firmware Package.
+//
+//*****************************************************************************
+
+#include <stdint.h>
+#include <stdbool.h>
+#include "random.h"
+
+//*****************************************************************************
+//
+// The pool of entropy that has been collected.
+//
+//*****************************************************************************
+static uint32_t g_pui32RandomEntropy[16];
+
+//*****************************************************************************
+//
+// The index of the next byte to be added to the entropy pool.
+//
+//*****************************************************************************
+static uint32_t g_ui32RandomIndex = 0;
+
+//*****************************************************************************
+//
+// The random number seed, which corresponds to the most recently returned
+// random number. This is set based on the entropy-generated random number
+// by RandomSeed().
+//
+//*****************************************************************************
+static uint32_t g_ui32RandomSeed = 0;
+
+//*****************************************************************************
+//
+// Add entropy to the pool.
+//
+//*****************************************************************************
+void
+RandomAddEntropy(uint32_t ui32Entropy)
+{
+ //
+ // Add this byte to the entropy pool.
+ //
+ ((uint8_t *)g_pui32RandomEntropy)[g_ui32RandomIndex] = ui32Entropy & 0xff;
+
+ //
+ // Increment to the next byte of the entropy pool.
+ //
+ g_ui32RandomIndex = (g_ui32RandomIndex + 1) & 63;
+}
+
+//*****************************************************************************
+//
+// Seed the random number generator by running a MD4 hash on the entropy pool.
+// Note that the entropy pool may change from beneath us, but for the purposes
+// of generating random numbers that is not a concern. Also, the MD4 hash was
+// broken long ago, but since it is being used to generate random numbers
+// instead of providing security this is not a concern.
+//
+//*****************************************************************************
+void
+RandomSeed(void)
+{
+ uint32_t ui32A, ui32B, ui32C, ui32D, ui32Temp, ui32Idx;
+
+ //
+ // Initialize the digest.
+ //
+ ui32A = 0x67452301;
+ ui32B = 0xefcdab89;
+ ui32C = 0x98badcfe;
+ ui32D = 0x10325476;
+
+ //
+ // Perform the first round of operations.
+ //
+#define F(a, b, c, d, k, s) \
+ { \
+ ui32Temp = a + (d ^ (b & (c ^ d))) + g_pui32RandomEntropy[k]; \
+ a = (ui32Temp << s) | (ui32Temp >> (32 - s)); \
+ }
+ for(ui32Idx = 0; ui32Idx < 16; ui32Idx += 4)
+ {
+ F(ui32A, ui32B, ui32C, ui32D, ui32Idx + 0, 3);
+ F(ui32D, ui32A, ui32B, ui32C, ui32Idx + 1, 7);
+ F(ui32C, ui32D, ui32A, ui32B, ui32Idx + 2, 11);
+ F(ui32B, ui32C, ui32D, ui32A, ui32Idx + 3, 19);
+ }
+
+ //
+ // Perform the second round of operations.
+ //
+#define G(a, b, c, d, k, s) \
+ { \
+ ui32Temp = a + ((b & c) | (b & d) | (c & d)) + \
+ g_pui32RandomEntropy[k] + 0x5a827999; \
+ a = (ui32Temp << s) | (ui32Temp >> (32 - s)); \
+ }
+ for(ui32Idx = 0; ui32Idx < 4; ui32Idx++)
+ {
+ G(ui32A, ui32B, ui32C, ui32D, ui32Idx + 0, 3);
+ G(ui32D, ui32A, ui32B, ui32C, ui32Idx + 4, 5);
+ G(ui32C, ui32D, ui32A, ui32B, ui32Idx + 8, 9);
+ G(ui32B, ui32C, ui32D, ui32A, ui32Idx + 12, 13);
+ }
+
+ //
+ // Perform the third round of operations.
+ //
+#define H(a, b, c, d, k, s) \
+ { \
+ ui32Temp = a + (b ^ c ^ d) + g_pui32RandomEntropy[k] + 0x6ed9eba1; \
+ a = (ui32Temp << s) | (ui32Temp >> (32 - s)); \
+ }
+ for(ui32Idx = 0; ui32Idx < 4; ui32Idx += 2)
+ {
+ H(ui32A, ui32B, ui32C, ui32D, ui32Idx + 0, 3);
+ H(ui32D, ui32A, ui32B, ui32C, ui32Idx + 8, 9);
+ H(ui32C, ui32D, ui32A, ui32B, ui32Idx + 4, 11);
+ H(ui32B, ui32C, ui32D, ui32A, ui32Idx + 12, 15);
+
+ if(ui32Idx == 2)
+ {
+ ui32Idx -= 3;
+ }
+ }
+
+ //
+ // Use the first word of the resulting digest as the random number seed.
+ //
+ g_ui32RandomSeed = ui32A + 0x67452301;
+}
+
+//*****************************************************************************
+//
+// Generate a new random number. The number returned would more accruately be
+// described as a pseudo-random number since a linear congruence generator is
+// being used.
+//
+//*****************************************************************************
+uint32_t
+RandomNumber(void)
+{
+ //
+ // Generate a new pseudo-random number with a linear congruence random
+ // number generator. This new random number becomes the seed for the next
+ // random number.
+ //
+ g_ui32RandomSeed = (g_ui32RandomSeed * 1664525) + 1013904223;
+
+ //
+ // Return the new random number.
+ //
+ return(g_ui32RandomSeed);
+}
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