Add crc32 and md5 to test lib
authorAndreas Schiffler <aschiffler@ferzkopp.net>
Wed, 28 Nov 2012 19:19:57 -0800
changeset 6713 fa17a97389ed
parent 6712 05f046f5886b
child 6714 146d1d7ecdc4
Add crc32 and md5 to test lib
include/SDL_test.h
include/SDL_test_crc32.h
include/SDL_test_md5.h
include/SDL_test_random.h
src/test/SDL_test_crc32.c
src/test/SDL_test_md5.c
--- a/include/SDL_test.h	Wed Nov 28 11:52:38 2012 -0800
+++ b/include/SDL_test.h	Wed Nov 28 19:19:57 2012 -0800
@@ -20,20 +20,22 @@
 */
 
 /**
- *  \file SDLTest.h
+ *  \file SDL_test.h
  *  
  *  Include file for SDL test framework.
  *
  *  This code is a part of the SDL2_test library, not the main SDL library.
  */
 
-#ifndef _SDLTest_h
-#define _SDLTest_h
+#ifndef _SDL_test_h
+#define _SDL_test_h
 
 #include "SDL.h"
 #include "SDL_test_font.h"
 #include "SDL_test_random.h"
 #include "SDL_test_fuzzer.h"
+#include "SDL_test_crc32.h"
+#include "SDL_test_md5.h"
 
 #include "begin_code.h"
 /* Set up for C function definitions, even when using C++ */
@@ -55,6 +57,6 @@
 #endif
 #include "close_code.h"
 
-#endif /* _SDLTest_h */
+#endif /* _SDL_test_h */
 
 /* vi: set ts=4 sw=4 expandtab: */
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/include/SDL_test_crc32.h	Wed Nov 28 19:19:57 2012 -0800
@@ -0,0 +1,128 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2012 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+/**
+ *  \file SDL_test_crc32.h
+ *  
+ *  Include file for SDL test framework.
+ *
+ *  This code is a part of the SDL2_test library, not the main SDL library.
+ */
+
+/* 
+
+ Implements CRC32 calculations (default output is Perl String::CRC32 compatible).
+  
+*/
+
+#ifndef _SDL_test_crc32_h
+#define _SDL_test_crc32_h
+
+#include "begin_code.h"
+/* Set up for C function definitions, even when using C++ */
+#ifdef __cplusplus
+/* *INDENT-OFF* */
+extern "C" {
+/* *INDENT-ON* */
+#endif
+
+
+/* ------------ Definitions --------- */
+
+/* Definition shared by all CRC routines */
+
+#ifndef CrcUint32
+ #define CrcUint32	unsigned int
+#endif
+#ifndef CrcUint8
+ #define CrcUint8	unsigned char
+#endif
+
+#ifdef ORIGINAL_METHOD
+ #define CRC32_POLY 0x04c11db7 	 /* AUTODIN II, Ethernet, & FDDI */
+#else
+ #define CRC32_POLY 0xEDB88320   /* Perl String::CRC32 compatible */
+#endif
+
+/** 
+ * Data structure for CRC32 (checksum) computation 
+ */
+  typedef struct {
+    CrcUint32    crc32_table[256]; /* CRC table */
+  } SDLTest_Crc32Context;
+
+/* ---------- Function Prototypes ------------- */
+
+/** 
+ * /brief Initialize the CRC context
+ *
+ * Note: The function initializes the crc table required for all crc calculations.
+ *
+ * /param crcContext		pointer to context variable
+ *
+ * /returns 0 for OK, -1 on error
+ *
+ */
+ int SDLTest_Crc32Init(SDLTest_Crc32Context * crcContext);
+
+
+/**
+ * /brief calculate a crc32 from a data block
+ * 
+ * /param crcContext	     pointer to context variable
+ * /param inBuf              input buffer to checksum
+ * /param inLen              length of input buffer
+ * /param crc32              pointer to Uint32 to store the final CRC into
+ *
+ * /returns 0 for OK, -1 on error
+ *
+ */
+int SDLTest_crc32Calc(SDLTest_Crc32Context * crcContext, CrcUint8 *inBuf, CrcUint32 inLen, CrcUint32 *crc32);
+
+/* Same routine broken down into three steps */
+int SDLTest_Crc32CalcStart(SDLTest_Crc32Context * crcContext, CrcUint32 *crc32);
+int SDLTest_Crc32CalcEnd(SDLTest_Crc32Context * crcContext, CrcUint32 *crc32);
+int SDLTest_Crc32CalcBuffer(SDLTest_Crc32Context * crcContext, CrcUint8 *inBuf, CrcUint32 inLen, CrcUint32 *crc32);
+
+
+/**
+ * /brief clean up CRC context
+ *
+ * /param crcContext		pointer to context variable
+ *
+ * /returns 0 for OK, -1 on error
+ *
+*/
+
+int SDLTest_Crc32Done(SDLTest_Crc32Context * crcContext);
+
+
+/* Ends C function definitions when using C++ */
+#ifdef __cplusplus
+/* *INDENT-OFF* */
+}
+/* *INDENT-ON* */
+#endif
+#include "close_code.h"
+
+#endif /* _SDL_test_crc32_h */
+
+/* vi: set ts=4 sw=4 expandtab: */
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/include/SDL_test_md5.h	Wed Nov 28 19:19:57 2012 -0800
@@ -0,0 +1,133 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2012 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+/**
+ *  \file SDL_test_md5.h
+ *  
+ *  Include file for SDL test framework.
+ *
+ *  This code is a part of the SDL2_test library, not the main SDL library.
+ */
+
+/*
+ ***********************************************************************
+ ** Header file for implementation of MD5                             **
+ ** RSA Data Security, Inc. MD5 Message-Digest Algorithm              **
+ ** Created: 2/17/90 RLR                                              **
+ ** Revised: 12/27/90 SRD,AJ,BSK,JT Reference C version               **
+ ** Revised (for MD5): RLR 4/27/91                                    **
+ **   -- G modified to have y&~z instead of y&z                       **
+ **   -- FF, GG, HH modified to add in last register done             **
+ **   -- Access pattern: round 2 works mod 5, round 3 works mod 3     **
+ **   -- distinct additive constant for each step                     **
+ **   -- round 4 added, working mod 7                                 **
+ ***********************************************************************
+*/
+
+/*
+ ***********************************************************************
+ **  Message-digest routines:                                         **
+ **  To form the message digest for a message M                       **
+ **    (1) Initialize a context buffer mdContext using MD5Init        **
+ **    (2) Call MD5Update on mdContext and M                          **
+ **    (3) Call MD5Final on mdContext                                 **
+ **  The message digest is now in mdContext->digest[0...15]           **
+ ***********************************************************************
+*/
+
+#ifndef _SDL_test_md5_h
+#define _SDL_test_md5_h
+
+#include "begin_code.h"
+/* Set up for C function definitions, even when using C++ */
+#ifdef __cplusplus
+/* *INDENT-OFF* */
+extern "C" {
+/* *INDENT-ON* */
+#endif
+
+/* ------------ Definitions --------- */
+
+/* typedef a 32-bit type */
+  typedef unsigned long int MD5UINT4;
+
+/* Data structure for MD5 (Message-Digest) computation */
+  typedef struct {
+    MD5UINT4  i[2];		/* number of _bits_ handled mod 2^64 */
+    MD5UINT4  buf[4];		/* scratch buffer */
+    unsigned char in[64];	/* input buffer */
+    unsigned char digest[16];	/* actual digest after Md5Final call */
+  } SDLTest_Md5Context;
+
+/* ---------- Function Prototypes ------------- */
+
+/** 
+ * /brief initialize the context
+ *
+ * /param  mdContext		pointer to context variable
+ *
+ * Note: The function initializes the message-digest context
+ *       mdContext. Call before each new use of the context - 
+ *       all fields are set to zero.
+ */
+ void SDLTest_Md5Init(SDLTest_Md5Context * mdContext);
+
+
+/**
+ * /brief update digest from variable length data
+ * 
+ * /param  mdContext       pointer to context variable
+ * /param  inBuf           pointer to data array/string
+ * /param  inLen           length of data array/string
+ *
+ * Note: The function updates the message-digest context to account 
+ *       for the presence of each of the characters inBuf[0..inLen-1]
+ *       in the message whose digest is being computed.
+*/
+
+ void SDLTest_Md5Update(SDLTest_Md5Context * mdContext, unsigned char *inBuf,
+				 unsigned int inLen);
+
+
+/*
+ * /brief complete digest computation
+ *
+ * /param mdContext		pointer to context variable
+ *
+ * Note: The function terminates the message-digest computation and
+ *       ends with the desired message digest in mdContext.digest[0..15].
+ *       Always call before using the digest[] variable.
+*/
+
+ void SDLTest_Md5Final(SDLTest_Md5Context * mdContext);
+
+
+/* Ends C function definitions when using C++ */
+#ifdef __cplusplus
+/* *INDENT-OFF* */
+}
+/* *INDENT-ON* */
+#endif
+#include "close_code.h"
+
+#endif /* _SDL_test_md5_h */
+
+/* vi: set ts=4 sw=4 expandtab: */
--- a/include/SDL_test_random.h	Wed Nov 28 11:52:38 2012 -0800
+++ b/include/SDL_test_random.h	Wed Nov 28 19:19:57 2012 -0800
@@ -48,10 +48,7 @@
 /* *INDENT-ON* */
 #endif
 
-/* Function prototypes */
-
-
-/* ------- Definitions ------- */
+/* --- Definitions */
 
 /*
  * Macros that return a random number in a specific format.
@@ -69,13 +66,14 @@
     unsigned int al;
   } SDLTest_RandomContext;
 
-/* ---- Function Prototypes -------- */
+
+/* --- Function prototypes */
 
 /**
  *  \brief Initialize random number generator with two integers. 
  *
- * Note: The random sequence of numbers returned by ...Random() is the
- *       same for the same two integers and has a period of 2^31.
+ *  Note: The random sequence of numbers returned by ...Random() is the
+ *  same for the same two integers and has a period of 2^31.
  *
  *  \param rndContext     pointer to context structure
  *  \param xi         integer that defines the random sequence
@@ -97,8 +95,8 @@
 /**
  *  \brief Initialize random number generator based on current system time. 
  *
- * Note: ...RandomInit() or ...RandomInitTime() must have been called
- *       before using this function.
+ *  Note: ...RandomInit() or ...RandomInitTime() must have been called
+ *  before using this function.
  *
  *  \param rndContext     pointer to context structure
  *
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/test/SDL_test_crc32.c	Wed Nov 28 19:19:57 2012 -0800
@@ -0,0 +1,165 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2012 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+/*
+
+ Used by the test execution component. 
+ Original source code contributed by A. Schiffler for GSOC project.
+
+*/
+
+#include "SDL_config.h"
+
+#include "SDL_test.h"
+
+
+int SDLTest_Crc32Init(SDLTest_Crc32Context *crcContext)
+{
+  int i,j;
+  CrcUint32 c;
+
+  /* Sanity check context pointer */
+  if (crcContext==NULL) {
+   return -1;
+  }  
+ 
+  /*
+   * Build auxiliary table for parallel byte-at-a-time CRC-32 
+   */
+#ifdef ORIGINAL_METHOD
+  for (i = 0; i < 256; ++i) {
+    for (c = i << 24, j = 8; j > 0; --j) {
+      c = c & 0x80000000 ? (c << 1) ^ CRC32_POLY : (c << 1);
+    }
+    crcContext->crc32_table[i] = c;
+  }
+#else
+  for (i=0; i<256; i++) {
+   c = i;
+   for (j=8; j>0; j--) {
+    if (c & 1) {
+     c = (c >> 1) ^ CRC32_POLY;
+    } else {
+     c >>= 1;
+    }
+   }
+   crcContext->crc32_table[i] = c;
+  }
+#endif
+  
+  return 0;
+}
+
+/* Complete CRC32 calculation on a memory block */
+
+int SDLTest_Crc32Calc(SDLTest_Crc32Context * crcContext, CrcUint8 *inBuf, CrcUint32 inLen, CrcUint32 *crc32)
+{
+  if (SDLTest_Crc32CalcStart(crcContext,crc32)) {
+   return -1;
+  }
+  
+  if (SDLTest_Crc32CalcBuffer(crcContext, inBuf, inLen, crc32)) {
+   return -1;
+  }
+  
+  if (SDLTest_Crc32CalcEnd(crcContext, crc32)) {
+   return -1;
+  }
+   
+  return 0;
+}
+
+/* Start crc calculation */
+
+int SDLTest_Crc32CalcStart(SDLTest_Crc32Context * crcContext, CrcUint32 *crc32)
+{
+  /* Sanity check pointers */
+  if (crcContext==NULL) {
+   *crc32=0;
+   return -1;
+  }  
+
+  /*
+   * Preload shift register, per CRC-32 spec 
+   */
+  *crc32 = 0xffffffff;
+
+  return 0;
+}
+
+/* Finish crc calculation */
+
+int SDLTest_Crc32CalcEnd(SDLTest_Crc32Context * crcContext, CrcUint32 *crc32)
+{
+  /* Sanity check pointers */
+  if (crcContext==NULL) {
+   *crc32=0;
+   return -1;
+  }  
+  
+  /*
+   * Return complement, per CRC-32 spec 
+   */
+  *crc32 = (~(*crc32));
+
+  return 0;
+}
+
+/* Include memory block in crc */
+
+int SDLTest_Crc32CalcBuffer(SDLTest_Crc32Context * crcContext, CrcUint8 *inBuf, CrcUint32 inLen, CrcUint32 *crc32)
+{
+  CrcUint8    *p;
+  register CrcUint32    crc;
+
+  if (crcContext==NULL) {
+   *crc32=0;
+   return -1;
+  }
+  
+  if (inBuf==NULL) {
+   return -1;
+  }
+
+  /*
+   * Calculate CRC from data 
+   */
+  crc = *crc32;
+  for (p = inBuf; inLen > 0; ++p, --inLen) {
+#ifdef ORIGINAL_METHOD  
+    crc = (crc << 8) ^ crcContext->crc32_table[(crc >> 24) ^ *p];
+#else
+    crc = ((crc >> 8) & 0x00FFFFFF) ^ crcContext->crc32_table[ (crc ^ *p) & 0xFF ];
+#endif         
+  }  
+  *crc32 = crc;
+  
+  return 0;
+}
+
+int SDLTest_Crc32Done(SDLTest_Crc32Context * crcContext)
+{
+  if (crcContext==NULL) {
+     return -1;
+  }  
+
+  return 0;
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/test/SDL_test_md5.c	Wed Nov 28 19:19:57 2012 -0800
@@ -0,0 +1,336 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2012 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+/*
+ ***********************************************************************
+ ** RSA Data Security, Inc. MD5 Message-Digest Algorithm              **
+ ** Created: 2/17/90 RLR                                              **
+ ** Revised: 1/91 SRD,AJ,BSK,JT Reference C ver., 7/10 constant corr. **
+ ***********************************************************************
+ */
+
+/*
+ ***********************************************************************
+ ** Copyright (C) 1990, RSA Data Security, Inc. All rights reserved.  **
+ **                                                                   **
+ ** License to copy and use this software is granted provided that    **
+ ** it is identified as the "RSA Data Security, Inc. MD5 Message-     **
+ ** Digest Algorithm" in all material mentioning or referencing this  **
+ ** software or this function.                                        **
+ **                                                                   **
+ ** License is also granted to make and use derivative works          **
+ ** provided that such works are identified as "derived from the RSA  **
+ ** Data Security, Inc. MD5 Message-Digest Algorithm" in all          **
+ ** material mentioning or referencing the derived work.              **
+ **                                                                   **
+ ** RSA Data Security, Inc. makes no representations concerning       **
+ ** either the merchantability of this software or the suitability    **
+ ** of this software for any particular purpose.  It is provided "as  **
+ ** is" without express or implied warranty of any kind.              **
+ **                                                                   **
+ ** These notices must be retained in any copies of any part of this  **
+ ** documentation and/or software.                                    **
+ ***********************************************************************
+ */
+
+#include "SDL_config.h"
+
+#include "SDL_test.h"
+
+/* Forward declaration of static helper function */
+static void SDLTest_Md5Transform(MD5UINT4 * buf, MD5UINT4 * in);
+
+static unsigned char MD5PADDING[64] = {
+  0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+};
+
+/* F, G, H and I are basic MD5 functions */
+#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
+#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
+#define H(x, y, z) ((x) ^ (y) ^ (z))
+#define I(x, y, z) ((y) ^ ((x) | (~z)))
+
+/* ROTATE_LEFT rotates x left n bits */
+#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))
+
+/* FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4 */
+
+/* Rotation is separate from addition to prevent recomputation */
+#define FF(a, b, c, d, x, s, ac) \
+  {(a) += F ((b), (c), (d)) + (x) + (MD5UINT4)(ac); \
+   (a) = ROTATE_LEFT ((a), (s)); \
+   (a) += (b); \
+  }
+#define GG(a, b, c, d, x, s, ac) \
+  {(a) += G ((b), (c), (d)) + (x) + (MD5UINT4)(ac); \
+   (a) = ROTATE_LEFT ((a), (s)); \
+   (a) += (b); \
+  }
+#define HH(a, b, c, d, x, s, ac) \
+  {(a) += H ((b), (c), (d)) + (x) + (MD5UINT4)(ac); \
+   (a) = ROTATE_LEFT ((a), (s)); \
+   (a) += (b); \
+  }
+#define II(a, b, c, d, x, s, ac) \
+  {(a) += I ((b), (c), (d)) + (x) + (MD5UINT4)(ac); \
+   (a) = ROTATE_LEFT ((a), (s)); \
+   (a) += (b); \
+  }
+
+/* 
+  The routine MD5Init initializes the message-digest context
+  mdContext. All fields are set to zero.
+*/
+
+void SDLTest_Md5Init(SDLTest_Md5Context * mdContext)
+{
+  if (mdContext==NULL) return;
+
+  mdContext->i[0] = mdContext->i[1] = (MD5UINT4) 0;
+
+  /*
+   * Load magic initialization constants.
+   */
+  mdContext->buf[0] = (MD5UINT4) 0x67452301;
+  mdContext->buf[1] = (MD5UINT4) 0xefcdab89;
+  mdContext->buf[2] = (MD5UINT4) 0x98badcfe;
+  mdContext->buf[3] = (MD5UINT4) 0x10325476;
+}
+
+/* 
+ The routine MD5Update updates the message-digest context to
+ account for the presence of each of the characters inBuf[0..inLen-1]
+ in the message whose digest is being computed.
+*/
+
+void SDLTest_Md5Update(SDLTest_Md5Context * mdContext, unsigned char *inBuf,
+		  unsigned int inLen)
+{
+  MD5UINT4  in[16];
+  int       mdi;
+  unsigned int i, ii;
+
+  if (mdContext == NULL) return;
+  if (inBuf == NULL || inLen < 1) return;
+
+  /*
+   * compute number of bytes mod 64 
+   */
+  mdi = (int) ((mdContext->i[0] >> 3) & 0x3F);
+
+  /*
+   * update number of bits 
+   */
+  if ((mdContext->i[0] + ((MD5UINT4) inLen << 3)) < mdContext->i[0])
+    mdContext->i[1]++;
+  mdContext->i[0] += ((MD5UINT4) inLen << 3);
+  mdContext->i[1] += ((MD5UINT4) inLen >> 29);
+
+  while (inLen--) {
+    /*
+     * add new character to buffer, increment mdi 
+     */
+    mdContext->in[mdi++] = *inBuf++;
+
+    /*
+     * transform if necessary 
+     */
+    if (mdi == 0x40) {
+      for (i = 0, ii = 0; i < 16; i++, ii += 4)
+	in[i] = (((MD5UINT4) mdContext->in[ii + 3]) << 24) |
+	  (((MD5UINT4) mdContext->in[ii + 2]) << 16) |
+	  (((MD5UINT4) mdContext->in[ii + 1]) << 8) |
+	  ((MD5UINT4) mdContext->in[ii]);
+      SDLTest_Md5Transform(mdContext->buf, in);
+      mdi = 0;
+    }
+  }
+}
+
+/* 
+ The routine MD5Final terminates the message-digest computation and
+ ends with the desired message digest in mdContext->digest[0...15].
+*/
+
+void SDLTest_Md5Final(SDLTest_Md5Context * mdContext)
+{
+  MD5UINT4  in[16];
+  int       mdi;
+  unsigned int i, ii;
+  unsigned int padLen;
+
+  if (mdContext == NULL) return;
+
+  /*
+   * save number of bits 
+   */
+  in[14] = mdContext->i[0];
+  in[15] = mdContext->i[1];
+
+  /*
+   * compute number of bytes mod 64 
+   */
+  mdi = (int) ((mdContext->i[0] >> 3) & 0x3F);
+
+  /*
+   * pad out to 56 mod 64 
+   */
+  padLen = (mdi < 56) ? (56 - mdi) : (120 - mdi);
+  SDLTest_Md5Update(mdContext, MD5PADDING, padLen);
+
+  /*
+   * append length in bits and transform 
+   */
+  for (i = 0, ii = 0; i < 14; i++, ii += 4)
+    in[i] = (((MD5UINT4) mdContext->in[ii + 3]) << 24) |
+      (((MD5UINT4) mdContext->in[ii + 2]) << 16) |
+      (((MD5UINT4) mdContext->in[ii + 1]) << 8) |
+      ((MD5UINT4) mdContext->in[ii]);
+  SDLTest_Md5Transform(mdContext->buf, in);
+
+  /*
+   * store buffer in digest 
+   */
+  for (i = 0, ii = 0; i < 4; i++, ii += 4) {
+    mdContext->digest[ii] = (unsigned char) (mdContext->buf[i] & 0xFF);
+    mdContext->digest[ii + 1] =
+      (unsigned char) ((mdContext->buf[i] >> 8) & 0xFF);
+    mdContext->digest[ii + 2] =
+      (unsigned char) ((mdContext->buf[i] >> 16) & 0xFF);
+    mdContext->digest[ii + 3] =
+      (unsigned char) ((mdContext->buf[i] >> 24) & 0xFF);
+  }
+}
+
+/* Basic MD5 step. Transforms buf based on in.
+ */
+static void SDLTest_Md5Transform(MD5UINT4 * buf, MD5UINT4 * in)
+{
+  MD5UINT4  a = buf[0], b = buf[1], c = buf[2], d = buf[3];
+
+  /*
+   * Round 1 
+   */
+#define S11 7
+#define S12 12
+#define S13 17
+#define S14 22
+  FF(a, b, c, d, in[0], S11, 3614090360u);	/* 1 */
+  FF(d, a, b, c, in[1], S12, 3905402710u);	/* 2 */
+  FF(c, d, a, b, in[2], S13, 606105819u);	/* 3 */
+  FF(b, c, d, a, in[3], S14, 3250441966u);	/* 4 */
+  FF(a, b, c, d, in[4], S11, 4118548399u);	/* 5 */
+  FF(d, a, b, c, in[5], S12, 1200080426u);	/* 6 */
+  FF(c, d, a, b, in[6], S13, 2821735955u);	/* 7 */
+  FF(b, c, d, a, in[7], S14, 4249261313u);	/* 8 */
+  FF(a, b, c, d, in[8], S11, 1770035416u);	/* 9 */
+  FF(d, a, b, c, in[9], S12, 2336552879u);	/* 10 */
+  FF(c, d, a, b, in[10], S13, 4294925233u);	/* 11 */
+  FF(b, c, d, a, in[11], S14, 2304563134u);	/* 12 */
+  FF(a, b, c, d, in[12], S11, 1804603682u);	/* 13 */
+  FF(d, a, b, c, in[13], S12, 4254626195u);	/* 14 */
+  FF(c, d, a, b, in[14], S13, 2792965006u);	/* 15 */
+  FF(b, c, d, a, in[15], S14, 1236535329u);	/* 16 */
+
+  /*
+   * Round 2 
+   */
+#define S21 5
+#define S22 9
+#define S23 14
+#define S24 20
+  GG(a, b, c, d, in[1], S21, 4129170786u);	/* 17 */
+  GG(d, a, b, c, in[6], S22, 3225465664u);	/* 18 */
+  GG(c, d, a, b, in[11], S23, 643717713u);	/* 19 */
+  GG(b, c, d, a, in[0], S24, 3921069994u);	/* 20 */
+  GG(a, b, c, d, in[5], S21, 3593408605u);	/* 21 */
+  GG(d, a, b, c, in[10], S22, 38016083u);	/* 22 */
+  GG(c, d, a, b, in[15], S23, 3634488961u);	/* 23 */
+  GG(b, c, d, a, in[4], S24, 3889429448u);	/* 24 */
+  GG(a, b, c, d, in[9], S21, 568446438u);	/* 25 */
+  GG(d, a, b, c, in[14], S22, 3275163606u);	/* 26 */
+  GG(c, d, a, b, in[3], S23, 4107603335u);	/* 27 */
+  GG(b, c, d, a, in[8], S24, 1163531501u);	/* 28 */
+  GG(a, b, c, d, in[13], S21, 2850285829u);	/* 29 */
+  GG(d, a, b, c, in[2], S22, 4243563512u);	/* 30 */
+  GG(c, d, a, b, in[7], S23, 1735328473u);	/* 31 */
+  GG(b, c, d, a, in[12], S24, 2368359562u);	/* 32 */
+
+  /*
+   * Round 3 
+   */
+#define S31 4
+#define S32 11
+#define S33 16
+#define S34 23
+  HH(a, b, c, d, in[5], S31, 4294588738u);	/* 33 */
+  HH(d, a, b, c, in[8], S32, 2272392833u);	/* 34 */
+  HH(c, d, a, b, in[11], S33, 1839030562u);	/* 35 */
+  HH(b, c, d, a, in[14], S34, 4259657740u);	/* 36 */
+  HH(a, b, c, d, in[1], S31, 2763975236u);	/* 37 */
+  HH(d, a, b, c, in[4], S32, 1272893353u);	/* 38 */
+  HH(c, d, a, b, in[7], S33, 4139469664u);	/* 39 */
+  HH(b, c, d, a, in[10], S34, 3200236656u);	/* 40 */
+  HH(a, b, c, d, in[13], S31, 681279174u);	/* 41 */
+  HH(d, a, b, c, in[0], S32, 3936430074u);	/* 42 */
+  HH(c, d, a, b, in[3], S33, 3572445317u);	/* 43 */
+  HH(b, c, d, a, in[6], S34, 76029189u);	/* 44 */
+  HH(a, b, c, d, in[9], S31, 3654602809u);	/* 45 */
+  HH(d, a, b, c, in[12], S32, 3873151461u);	/* 46 */
+  HH(c, d, a, b, in[15], S33, 530742520u);	/* 47 */
+  HH(b, c, d, a, in[2], S34, 3299628645u);	/* 48 */
+
+  /*
+   * Round 4 
+   */
+#define S41 6
+#define S42 10
+#define S43 15
+#define S44 21
+  II(a, b, c, d, in[0], S41, 4096336452u);	/* 49 */
+  II(d, a, b, c, in[7], S42, 1126891415u);	/* 50 */
+  II(c, d, a, b, in[14], S43, 2878612391u);	/* 51 */
+  II(b, c, d, a, in[5], S44, 4237533241u);	/* 52 */
+  II(a, b, c, d, in[12], S41, 1700485571u);	/* 53 */
+  II(d, a, b, c, in[3], S42, 2399980690u);	/* 54 */
+  II(c, d, a, b, in[10], S43, 4293915773u);	/* 55 */
+  II(b, c, d, a, in[1], S44, 2240044497u);	/* 56 */
+  II(a, b, c, d, in[8], S41, 1873313359u);	/* 57 */
+  II(d, a, b, c, in[15], S42, 4264355552u);	/* 58 */
+  II(c, d, a, b, in[6], S43, 2734768916u);	/* 59 */
+  II(b, c, d, a, in[13], S44, 1309151649u);	/* 60 */
+  II(a, b, c, d, in[4], S41, 4149444226u);	/* 61 */
+  II(d, a, b, c, in[11], S42, 3174756917u);	/* 62 */
+  II(c, d, a, b, in[2], S43, 718787259u);	/* 63 */
+  II(b, c, d, a, in[9], S44, 3951481745u);	/* 64 */
+
+  buf[0] += a;
+  buf[1] += b;
+  buf[2] += c;
+  buf[3] += d;
+}