diff --git a/reactos/lib/crtdll/float/cntrlfp.c b/reactos/lib/crtdll/float/cntrlfp.c
index 32b03935b26..c093d827e64 100644
--- a/reactos/lib/crtdll/float/cntrlfp.c
+++ b/reactos/lib/crtdll/float/cntrlfp.c
@@ -2,19 +2,149 @@
 
 #include <msvcrt/float.h>
 
+#define X87_CW_IM   (1<<0)      /* Invalid operation mask */
+#define X87_CW_DM   (1<<1)      /* Denormal operand mask */
+#define X87_CW_ZM   (1<<2)      /* Zero divide mask */
+#define X87_CW_OM   (1<<3)      /* Overflow mask */
+#define X87_CW_UM   (1<<4)      /* Underflow mask */
+#define X87_CW_PM   (1<<5)      /* Precision mask */
+
+#define X87_CW_PC_MASK     (3<<8)   /* precision control mask */
+#define X87_CW_PC24        (0<<8)   /* 24 bit precision */
+#define X87_CW_PC53        (2<<8)   /* 53 bit precision */
+#define X87_CW_PC64        (3<<8)   /* 64 bit precision */
+
+#define X87_CW_RC_MASK     (3<<10)  /* rounding control mask */
+#define X87_CW_RC_NEAREST  (0<<10)  /* round to nearest */
+#define X87_CW_RC_DOWN     (1<<10)  /* round down */
+#define X87_CW_RC_UP       (2<<10)  /* round up */
+#define X87_CW_RC_ZERO     (3<<10)  /* round toward zero (chop) */
+
+#define X87_CW_IC          (1<<12)  /* infinity control flag */
+
 /*
  * @implemented
  */
-unsigned int	_controlfp (unsigned int unNew, unsigned int unMask)
-{	
-	return _control87(unNew,unMask);
+unsigned int _controlfp(unsigned int unNew, unsigned int unMask)
+{
+  return _control87(unNew,unMask);
 }
 
 /*
  * @implemented
  */
-unsigned int	_control87 (unsigned int unNew, unsigned int unMask)
-{	
+unsigned int _control87(unsigned int unNew, unsigned int unMask)
+{
+  unsigned int FpuCw;
+  unsigned int DummyCw = 0;
+  
+  /* get the controlword */
+  asm volatile("fstcw %0\n\t" : "=m"(FpuCw));
+  FpuCw &= 0x0000ffff;
+  
+  /* translate it into _control87 format */
+  if (FpuCw & X87_CW_IM)
+    DummyCw |= _EM_INVALID;
+  if (FpuCw & X87_CW_DM)
+    DummyCw |= _EM_DENORMAL;
+  if (FpuCw & X87_CW_ZM)
+    DummyCw |= _EM_ZERODIVIDE;
+  if (FpuCw & X87_CW_OM)
+    DummyCw |= _EM_OVERFLOW;
+  if (FpuCw & X87_CW_UM)
+    DummyCw |= _EM_UNDERFLOW;
+  if (FpuCw & X87_CW_PM)
+    DummyCw |= _EM_INEXACT;
+
+  switch (FpuCw & X87_CW_PC_MASK)
+  {
+  case X87_CW_PC24:
+    DummyCw |= _PC_24;
+    break;
+  case X87_CW_PC53:
+    DummyCw |= _PC_53;
+    break;
+  case X87_CW_PC64:
+    DummyCw |= _PC_64;
+    break;
+  }
+
+  switch (FpuCw & X87_CW_RC_MASK)
+  {
+  case X87_CW_RC_NEAREST:
+    DummyCw |= _RC_NEAR;
+    break;
+  case X87_CW_RC_DOWN:
+    DummyCw |= _RC_DOWN;
+    break;
+  case X87_CW_RC_UP:
+    DummyCw |= _RC_UP;
+    break;
+  case X87_CW_RC_ZERO:
+    DummyCw |= _RC_CHOP;
+    break;
+  }
+
+  /* unset (un)masked bits */
+  DummyCw &= ~unMask;
+  unNew &= unMask;
+  
+  /* set new bits */
+  DummyCw |= unNew;
+  
+  /* translate back into x87 format
+   * FIXME: translate infinity control!
+   */
+  FpuCw = 0;
+  if (DummyCw & _EM_INVALID)
+    FpuCw |= X87_CW_IM;
+  if (DummyCw & _EM_DENORMAL)
+    FpuCw |= X87_CW_DM;
+  if (DummyCw & _EM_ZERODIVIDE)
+    FpuCw |= X87_CW_ZM;
+  if (DummyCw & _EM_OVERFLOW)
+    FpuCw |= X87_CW_OM;
+  if (DummyCw & _EM_UNDERFLOW)
+    FpuCw |= X87_CW_UM;
+  if (DummyCw & _EM_INEXACT)
+    FpuCw |= X87_CW_PM;
+
+  switch (DummyCw & _MCW_PC)
+  {
+  case _PC_24:
+    FpuCw |= X87_CW_PC24;
+    break;
+  case _PC_53:
+    FpuCw |= X87_CW_PC53;
+    break;
+  case _PC_64:
+  default:
+    FpuCw |= X87_CW_PC64;
+    break;
+  }
+
+  switch (DummyCw & _MCW_RC)
+  {
+  case _RC_NEAR:
+    FpuCw |= X87_CW_RC_NEAREST;
+    break;
+  case _RC_DOWN:
+    FpuCw |= X87_CW_RC_DOWN;
+    break;
+  case _RC_UP:
+    FpuCw |= X87_CW_RC_UP;
+    break;
+  case _RC_CHOP:
+    FpuCw |= X87_CW_RC_ZERO;
+    break;
+  }
+
+  /* set controlword */
+  asm volatile("fldcw %0" : : "m"(FpuCw));
+  
+  return DummyCw;
+
+#if 0 /* The follwing is the original code, broken I think! -blight */
 register unsigned int __res;
 #ifdef __GNUC__
 __asm__ __volatile__ (
@@ -36,8 +166,9 @@ __asm__ __volatile__ (
 	"fldcw	(%%esp) \n\t"
 	"popl	%%edx \n\t"
 
-	:"=r" (__res):"r" (unNew),"r" (unMask): "ax", "dx", "cx");
+	:"=a" (__res):"r" (unNew),"r" (unMask): "dx", "cx");
 #else
 #endif /*__GNUC__*/
 	return __res;
+#endif
 }
diff --git a/reactos/lib/msvcrt/float/cntrlfp.c b/reactos/lib/msvcrt/float/cntrlfp.c
index 3001221110b..c093d827e64 100644
--- a/reactos/lib/msvcrt/float/cntrlfp.c
+++ b/reactos/lib/msvcrt/float/cntrlfp.c
@@ -2,6 +2,26 @@
 
 #include <msvcrt/float.h>
 
+#define X87_CW_IM   (1<<0)      /* Invalid operation mask */
+#define X87_CW_DM   (1<<1)      /* Denormal operand mask */
+#define X87_CW_ZM   (1<<2)      /* Zero divide mask */
+#define X87_CW_OM   (1<<3)      /* Overflow mask */
+#define X87_CW_UM   (1<<4)      /* Underflow mask */
+#define X87_CW_PM   (1<<5)      /* Precision mask */
+
+#define X87_CW_PC_MASK     (3<<8)   /* precision control mask */
+#define X87_CW_PC24        (0<<8)   /* 24 bit precision */
+#define X87_CW_PC53        (2<<8)   /* 53 bit precision */
+#define X87_CW_PC64        (3<<8)   /* 64 bit precision */
+
+#define X87_CW_RC_MASK     (3<<10)  /* rounding control mask */
+#define X87_CW_RC_NEAREST  (0<<10)  /* round to nearest */
+#define X87_CW_RC_DOWN     (1<<10)  /* round down */
+#define X87_CW_RC_UP       (2<<10)  /* round up */
+#define X87_CW_RC_ZERO     (3<<10)  /* round toward zero (chop) */
+
+#define X87_CW_IC          (1<<12)  /* infinity control flag */
+
 /*
  * @implemented
  */
@@ -15,6 +35,116 @@ unsigned int _controlfp(unsigned int unNew, unsigned int unMask)
  */
 unsigned int _control87(unsigned int unNew, unsigned int unMask)
 {
+  unsigned int FpuCw;
+  unsigned int DummyCw = 0;
+  
+  /* get the controlword */
+  asm volatile("fstcw %0\n\t" : "=m"(FpuCw));
+  FpuCw &= 0x0000ffff;
+  
+  /* translate it into _control87 format */
+  if (FpuCw & X87_CW_IM)
+    DummyCw |= _EM_INVALID;
+  if (FpuCw & X87_CW_DM)
+    DummyCw |= _EM_DENORMAL;
+  if (FpuCw & X87_CW_ZM)
+    DummyCw |= _EM_ZERODIVIDE;
+  if (FpuCw & X87_CW_OM)
+    DummyCw |= _EM_OVERFLOW;
+  if (FpuCw & X87_CW_UM)
+    DummyCw |= _EM_UNDERFLOW;
+  if (FpuCw & X87_CW_PM)
+    DummyCw |= _EM_INEXACT;
+
+  switch (FpuCw & X87_CW_PC_MASK)
+  {
+  case X87_CW_PC24:
+    DummyCw |= _PC_24;
+    break;
+  case X87_CW_PC53:
+    DummyCw |= _PC_53;
+    break;
+  case X87_CW_PC64:
+    DummyCw |= _PC_64;
+    break;
+  }
+
+  switch (FpuCw & X87_CW_RC_MASK)
+  {
+  case X87_CW_RC_NEAREST:
+    DummyCw |= _RC_NEAR;
+    break;
+  case X87_CW_RC_DOWN:
+    DummyCw |= _RC_DOWN;
+    break;
+  case X87_CW_RC_UP:
+    DummyCw |= _RC_UP;
+    break;
+  case X87_CW_RC_ZERO:
+    DummyCw |= _RC_CHOP;
+    break;
+  }
+
+  /* unset (un)masked bits */
+  DummyCw &= ~unMask;
+  unNew &= unMask;
+  
+  /* set new bits */
+  DummyCw |= unNew;
+  
+  /* translate back into x87 format
+   * FIXME: translate infinity control!
+   */
+  FpuCw = 0;
+  if (DummyCw & _EM_INVALID)
+    FpuCw |= X87_CW_IM;
+  if (DummyCw & _EM_DENORMAL)
+    FpuCw |= X87_CW_DM;
+  if (DummyCw & _EM_ZERODIVIDE)
+    FpuCw |= X87_CW_ZM;
+  if (DummyCw & _EM_OVERFLOW)
+    FpuCw |= X87_CW_OM;
+  if (DummyCw & _EM_UNDERFLOW)
+    FpuCw |= X87_CW_UM;
+  if (DummyCw & _EM_INEXACT)
+    FpuCw |= X87_CW_PM;
+
+  switch (DummyCw & _MCW_PC)
+  {
+  case _PC_24:
+    FpuCw |= X87_CW_PC24;
+    break;
+  case _PC_53:
+    FpuCw |= X87_CW_PC53;
+    break;
+  case _PC_64:
+  default:
+    FpuCw |= X87_CW_PC64;
+    break;
+  }
+
+  switch (DummyCw & _MCW_RC)
+  {
+  case _RC_NEAR:
+    FpuCw |= X87_CW_RC_NEAREST;
+    break;
+  case _RC_DOWN:
+    FpuCw |= X87_CW_RC_DOWN;
+    break;
+  case _RC_UP:
+    FpuCw |= X87_CW_RC_UP;
+    break;
+  case _RC_CHOP:
+    FpuCw |= X87_CW_RC_ZERO;
+    break;
+  }
+
+  /* set controlword */
+  asm volatile("fldcw %0" : : "m"(FpuCw));
+  
+  return DummyCw;
+
+#if 0 /* The follwing is the original code, broken I think! -blight */
 register unsigned int __res;
 #ifdef __GNUC__
 __asm__ __volatile__ (
@@ -36,8 +166,9 @@ __asm__ __volatile__ (
 	"fldcw	(%%esp) \n\t"
 	"popl	%%edx \n\t"
 
-	:"=r" (__res):"r" (unNew),"r" (unMask): "ax", "dx", "cx");
+	:"=a" (__res):"r" (unNew),"r" (unMask): "dx", "cx");
 #else
 #endif /*__GNUC__*/
 	return __res;
+#endif
 }