[pschweitzer] 56791: [RTL] - Really implement RtlRandomEx and add its values table - Rename SavedValue to RtlpRandomConstantVector to allow RtlRandom & RtlRandomEx to have two different values tabl...
24 Jun
2012
24 Jun
'12
1:11 a.m.
Author: pschweitzer
Date: Sun Jun 24 01:10:58 2012
New Revision: 56791
URL: http://svn.reactos.org/svn/reactos?rev=56791&view=rev
Log:
[RTL]
- Really implement RtlRandomEx and add its values table
- Rename SavedValue to RtlpRandomConstantVector to allow RtlRandom & RtlRandomEx to
have two different values tables
- Complete and fix documentation
- Stop using magic values
Modified:
trunk/reactos/lib/rtl/random.c
Modified: trunk/reactos/lib/rtl/random.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/lib/rtl/random.c?rev=56791…
==============================================================================
--- trunk/reactos/lib/rtl/random.c [iso-8859-1] (original)
+++ trunk/reactos/lib/rtl/random.c [iso-8859-1] Sun Jun 24 01:10:58 2012
@@ -3,7 +3,8 @@
* PROJECT: ReactOS system libraries
* PURPOSE: Random number generator functions
* FILE: lib/rtl/random.c
- * PROGRAMMER:
+ * PROGRAMMER: Wine
+ * Pierre Schweitzer (pierre(a)reactos.org)
*/
/* INCLUDES *****************************************************************/
@@ -13,47 +14,91 @@
#define NDEBUG
#include <debug.h>
-static ULONG SavedValue[128] =
- {
- 0x4c8bc0aa, 0x4c022957, 0x2232827a, 0x2f1e7626, /* 0 */
- 0x7f8bdafb, 0x5c37d02a, 0x0ab48f72, 0x2f0c4ffa, /* 4 */
- 0x290e1954, 0x6b635f23, 0x5d3885c0, 0x74b49ff8, /* 8 */
- 0x5155fa54, 0x6214ad3f, 0x111e9c29, 0x242a3a09, /* 12 */
- 0x75932ae1, 0x40ac432e, 0x54f7ba7a, 0x585ccbd5, /* 16 */
- 0x6df5c727, 0x0374dad1, 0x7112b3f1, 0x735fc311, /* 20 */
- 0x404331a9, 0x74d97781, 0x64495118, 0x323e04be, /* 24 */
- 0x5974b425, 0x4862e393, 0x62389c1d, 0x28a68b82, /* 28 */
- 0x0f95da37, 0x7a50bbc6, 0x09b0091c, 0x22cdb7b4, /* 32 */
- 0x4faaed26, 0x66417ccd, 0x189e4bfa, 0x1ce4e8dd, /* 36 */
- 0x5274c742, 0x3bdcf4dc, 0x2d94e907, 0x32eac016, /* 40 */
- 0x26d33ca3, 0x60415a8a, 0x31f57880, 0x68c8aa52, /* 44 */
- 0x23eb16da, 0x6204f4a1, 0x373927c1, 0x0d24eb7c, /* 48 */
- 0x06dd7379, 0x2b3be507, 0x0f9c55b1, 0x2c7925eb, /* 52 */
- 0x36d67c9a, 0x42f831d9, 0x5e3961cb, 0x65d637a8, /* 56 */
- 0x24bb3820, 0x4d08e33d, 0x2188754f, 0x147e409e, /* 60 */
- 0x6a9620a0, 0x62e26657, 0x7bd8ce81, 0x11da0abb, /* 64 */
- 0x5f9e7b50, 0x23e444b6, 0x25920c78, 0x5fc894f0, /* 68 */
- 0x5e338cbb, 0x404237fd, 0x1d60f80f, 0x320a1743, /* 72 */
- 0x76013d2b, 0x070294ee, 0x695e243b, 0x56b177fd, /* 76 */
- 0x752492e1, 0x6decd52f, 0x125f5219, 0x139d2e78, /* 80 */
- 0x1898d11e, 0x2f7ee785, 0x4db405d8, 0x1a028a35, /* 84 */
- 0x63f6f323, 0x1f6d0078, 0x307cfd67, 0x3f32a78a, /* 88 */
- 0x6980796c, 0x462b3d83, 0x34b639f2, 0x53fce379, /* 92 */
- 0x74ba50f4, 0x1abc2c4b, 0x5eeaeb8d, 0x335a7a0d, /* 96 */
- 0x3973dd20, 0x0462d66b, 0x159813ff, 0x1e4643fd, /* 100 */
- 0x06bc5c62, 0x3115e3fc, 0x09101613, 0x47af2515, /* 104 */
- 0x4f11ec54, 0x78b99911, 0x3db8dd44, 0x1ec10b9b, /* 108 */
- 0x5b5506ca, 0x773ce092, 0x567be81a, 0x5475b975, /* 112 */
- 0x7a2cde1a, 0x494536f5, 0x34737bb4, 0x76d9750b, /* 116 */
- 0x2a1f6232, 0x2e49644d, 0x7dddcbe7, 0x500cebdb, /* 120 */
- 0x619dab9e, 0x48c626fe, 0x1cda3193, 0x52dabe9d /* 124 */
- };
-
+static ULONG RtlpRandomConstantVector[128] =
+{
+ 0x4c8bc0aa, 0x4c022957, 0x2232827a, 0x2f1e7626, /* 0 */
+ 0x7f8bdafb, 0x5c37d02a, 0x0ab48f72, 0x2f0c4ffa, /* 4 */
+ 0x290e1954, 0x6b635f23, 0x5d3885c0, 0x74b49ff8, /* 8 */
+ 0x5155fa54, 0x6214ad3f, 0x111e9c29, 0x242a3a09, /* 12 */
+ 0x75932ae1, 0x40ac432e, 0x54f7ba7a, 0x585ccbd5, /* 16 */
+ 0x6df5c727, 0x0374dad1, 0x7112b3f1, 0x735fc311, /* 20 */
+ 0x404331a9, 0x74d97781, 0x64495118, 0x323e04be, /* 24 */
+ 0x5974b425, 0x4862e393, 0x62389c1d, 0x28a68b82, /* 28 */
+ 0x0f95da37, 0x7a50bbc6, 0x09b0091c, 0x22cdb7b4, /* 32 */
+ 0x4faaed26, 0x66417ccd, 0x189e4bfa, 0x1ce4e8dd, /* 36 */
+ 0x5274c742, 0x3bdcf4dc, 0x2d94e907, 0x32eac016, /* 40 */
+ 0x26d33ca3, 0x60415a8a, 0x31f57880, 0x68c8aa52, /* 44 */
+ 0x23eb16da, 0x6204f4a1, 0x373927c1, 0x0d24eb7c, /* 48 */
+ 0x06dd7379, 0x2b3be507, 0x0f9c55b1, 0x2c7925eb, /* 52 */
+ 0x36d67c9a, 0x42f831d9, 0x5e3961cb, 0x65d637a8, /* 56 */
+ 0x24bb3820, 0x4d08e33d, 0x2188754f, 0x147e409e, /* 60 */
+ 0x6a9620a0, 0x62e26657, 0x7bd8ce81, 0x11da0abb, /* 64 */
+ 0x5f9e7b50, 0x23e444b6, 0x25920c78, 0x5fc894f0, /* 68 */
+ 0x5e338cbb, 0x404237fd, 0x1d60f80f, 0x320a1743, /* 72 */
+ 0x76013d2b, 0x070294ee, 0x695e243b, 0x56b177fd, /* 76 */
+ 0x752492e1, 0x6decd52f, 0x125f5219, 0x139d2e78, /* 80 */
+ 0x1898d11e, 0x2f7ee785, 0x4db405d8, 0x1a028a35, /* 84 */
+ 0x63f6f323, 0x1f6d0078, 0x307cfd67, 0x3f32a78a, /* 88 */
+ 0x6980796c, 0x462b3d83, 0x34b639f2, 0x53fce379, /* 92 */
+ 0x74ba50f4, 0x1abc2c4b, 0x5eeaeb8d, 0x335a7a0d, /* 96 */
+ 0x3973dd20, 0x0462d66b, 0x159813ff, 0x1e4643fd, /* 100 */
+ 0x06bc5c62, 0x3115e3fc, 0x09101613, 0x47af2515, /* 104 */
+ 0x4f11ec54, 0x78b99911, 0x3db8dd44, 0x1ec10b9b, /* 108 */
+ 0x5b5506ca, 0x773ce092, 0x567be81a, 0x5475b975, /* 112 */
+ 0x7a2cde1a, 0x494536f5, 0x34737bb4, 0x76d9750b, /* 116 */
+ 0x2a1f6232, 0x2e49644d, 0x7dddcbe7, 0x500cebdb, /* 120 */
+ 0x619dab9e, 0x48c626fe, 0x1cda3193, 0x52dabe9d /* 124 */
+};
+
+static ULONG RtlpRandomExConstantVector[128] =
+{
+ 0x4c8bc0aa, 0x51a0b326, 0x7112b3f1, 0x1b9ca4e1, /* 0 */
+ 0x735fc311, 0x6fe48580, 0x320a1743, 0x494045ca, /* 4 */
+ 0x103ad1c5, 0x4ba26e25, 0x62f1d304, 0x280d5677, /* 8 */
+ 0x070294ee, 0x7acef21a, 0x62a407d5, 0x2dd36af5, /* 12 */
+ 0x194f0f95, 0x1f21d7b4, 0x307cfd67, 0x66b9311e, /* 16 */
+ 0x60415a8a, 0x5b264785, 0x3c28b0e4, 0x08faded7, /* 20 */
+ 0x556175ce, 0x29c44179, 0x666f23c9, 0x65c057d8, /* 24 */
+ 0x72b97abc, 0x7c3be3d0, 0x478e1753, 0x3074449b, /* 28 */
+ 0x675ee842, 0x53f4c2de, 0x44d58949, 0x6426cf59, /* 32 */
+ 0x111e9c29, 0x3aba68b9, 0x242a3a09, 0x50ddb118, /* 36 */
+ 0x7f8bdafb, 0x089ebf23, 0x5c37d02a, 0x27db8ca6, /* 40 */
+ 0x0ab48f72, 0x34995a4e, 0x189e4bfa, 0x2c405c36, /* 44 */
+ 0x373927c1, 0x66c20c71, 0x5f991360, 0x67a38fa3, /* 48 */
+ 0x4edc56aa, 0x25a59126, 0x34b639f2, 0x1679b2ce, /* 52 */
+ 0x54f7ba7a, 0x319d28b5, 0x5155fa54, 0x769e6b87, /* 56 */
+ 0x323e04be, 0x4565a5aa, 0x5974b425, 0x5c56a104, /* 60 */
+ 0x25920c78, 0x362912dc, 0x7af3996f, 0x5feb9c87, /* 64 */
+ 0x618361bf, 0x433fbe97, 0x0244da8e, 0x54e3c739, /* 68 */
+ 0x33183689, 0x3533f398, 0x0d24eb7c, 0x06428590, /* 72 */
+ 0x09101613, 0x53ce5c5a, 0x47af2515, 0x2e003f35, /* 76 */
+ 0x15fb4ed5, 0x5e5925f4, 0x7f622ea7, 0x0bb6895f, /* 80 */
+ 0x2173cdb6, 0x0467bb41, 0x2c4d19f1, 0x364712e1, /* 84 */
+ 0x78b99911, 0x0a39a380, 0x3db8dd44, 0x6b4793b8, /* 88 */
+ 0x09b0091c, 0x47ef52b0, 0x293cdcb3, 0x707b9e7b, /* 92 */
+ 0x26d33ca3, 0x1e527faa, 0x3fe08625, 0x42560b04, /* 96 */
+ 0x139d2e78, 0x0b558cdb, 0x28a68b82, 0x7ba3a51d, /* 100 */
+ 0x52dabe9d, 0x59c3da1d, 0x5676cf9c, 0x152e972f, /* 104 */
+ 0x6d8ac746, 0x5eb33591, 0x78b30601, 0x0ab68db0, /* 108 */
+ 0x34737bb4, 0x1b6dd168, 0x76d9750b, 0x2ddc4ff2, /* 112 */
+ 0x18a610cd, 0x2bacc08c, 0x422db55f, 0x169b89b6, /* 116 */
+ 0x5274c742, 0x615535dd, 0x46ad005d, 0x4128f8dd, /* 120 */
+ 0x29f5875c, 0x62c6f3ef, 0x2b3be507, 0x4a8e003f /* 124 */
+};
+
+static ULONG RtlpRandomExAuxVarY = 0x7775fb16;
+
+#define LCG_A 0x7fffffed
+#define LCG_C 0x7fffffc3
+#define LCG_M MAXLONG
/*************************************************************************
* RtlRandom [NTDLL.@]
*
- * Generates a random number
+ * Generates a random number. This is based on a LCG.
+ * This makes it not suitable for Monte Carlo simulations nor
+ * cryptographic applications.
+ * See LCG_A, LCG_C, LCG_M for parameters.
*
* PARAMS
* Seed [O] The seed of the Random function
@@ -73,15 +118,30 @@
PAGED_CODE_RTL();
- Rand = (*Seed * 0x7fffffed + 0x7fffffc3) % 0x7fffffff;
- *Seed = (Rand * 0x7fffffed + 0x7fffffc3) % 0x7fffffff;
- Pos = *Seed & 0x7f;
- Result = SavedValue[Pos];
- SavedValue[Pos] = Rand;
+ Rand = (*Seed * LCG_A + LCG_C) % LCG_M;
+ *Seed = (Rand * LCG_A + LCG_C) % LCG_M;
+ Pos = *Seed & (sizeof(RtlpRandomConstantVector) /
sizeof(RtlpRandomConstantVector[0]) - 1);
+ Result = RtlpRandomConstantVector[Pos];
+ RtlpRandomConstantVector[Pos] = Rand;
return Result;
}
+/*************************************************************************
+ * RtlRandomEx [NTDLL.@]
+ *
+ * Generates a random number. This is based on a LCG.
+ * This makes it not suitable for Monte Carlo simulations nor
+ * cryptographic applications.
+ * This one is faster than RtlRandom.
+ * See LCG_A, LCG_C, LCG_M for parameters.
+ *
+ * PARAMS
+ * Seed [O] The seed of the Random function
+ *
+ * RETURNS
+ * It returns a random number distributed over [0..MAXLONG-1].
+ */
/*
* @implemented
*/
@@ -92,17 +152,16 @@
{
ULONG Rand;
int Pos;
- ULONG Result;
PAGED_CODE_RTL();
- Rand = (*Seed * 0x7fffffed + 0x7fffffc3) % 0x7fffffff;
- *Seed = (Rand * 0x7fffffed + 0x7fffffc3) % 0x7fffffff;
- Pos = *Seed & 0x7f;
- Result = SavedValue[Pos];
- SavedValue[Pos] = Rand;
-
- return Result;
+ Pos = RtlpRandomExAuxVarY & (sizeof(RtlpRandomExConstantVector) /
sizeof(RtlpRandomExConstantVector[0]) - 1);
+ RtlpRandomExAuxVarY = RtlpRandomExConstantVector[Pos];
+ Rand = (*Seed * LCG_A + LCG_C) % LCG_M;
+ RtlpRandomExConstantVector[Pos] = Rand;
+ *Seed = Rand;
+
+ return Rand;
}
@@ -119,12 +178,11 @@
* It returns a random number uniformly distributed over [0..MAXLONG-1].
*
* NOTES
- * Generates an uniform random number using D.H. Lehmer's 1948 algorithm.
- * In our case the algorithm is:
- *
- * Result = (*Seed * 0x7fffffed + 0x7fffffc3) % MAXLONG;
- *
- * *Seed = Result;
+ * Generates an uniform random number using LCG. In spite of what
+ * MSDN states, this is an LCG and not a Lehmer RNG since C is defined.
+ * This makes it not suitable for Monte Carlo simulations nor
+ * cryptographic applications.
+ * See LCG_A, LCG_C, LCG_M for parameters.
*
* DIFFERENCES
* The native documentation states that the random number is
@@ -139,7 +197,7 @@
ULONG Result;
/* Generate the random number */
- Result = (*Seed * 0x7fffffed + 0x7fffffc3) % MAXLONG;
+ Result = (*Seed * LCG_A + LCG_C) % LCG_M;
/* Return it */
*Seed = Result;
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pschweitzer＠svn.reactos.org