SDL  2.0
s_floor.c
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1 /*
2  * ====================================================
3  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
4  *
5  * Developed at SunPro, a Sun Microsystems, Inc. business.
6  * Permission to use, copy, modify, and distribute this
7  * software is freely granted, provided that this notice
8  * is preserved.
9  * ====================================================
10  */
11 
12 /*
13  * floor(x)
14  * Return x rounded toward -inf to integral value
15  * Method:
16  * Bit twiddling.
17  * Exception:
18  * Inexact flag raised if x not equal to floor(x).
19  */
20 
21 /*#include <features.h>*/
22 /* Prevent math.h from defining a colliding inline */
23 #undef __USE_EXTERN_INLINES
24 #include "math_libm.h"
25 #include "math_private.h"
26 
27 static const double huge = 1.0e300;
28 
29 double floor(double x)
30 {
31  int32_t i0,i1,j0;
32  u_int32_t i,j;
33  EXTRACT_WORDS(i0,i1,x);
34  j0 = ((i0>>20)&0x7ff)-0x3ff;
35  if(j0<20) {
36  if(j0<0) { /* raise inexact if x != 0 */
37  if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */
38  if(i0>=0) {i0=i1=0;}
39  else if(((i0&0x7fffffff)|i1)!=0)
40  { i0=0xbff00000;i1=0;}
41  }
42  } else {
43  i = (0x000fffff)>>j0;
44  if(((i0&i)|i1)==0) return x; /* x is integral */
45  if(huge+x>0.0) { /* raise inexact flag */
46  if(i0<0) i0 += (0x00100000)>>j0;
47  i0 &= (~i); i1=0;
48  }
49  }
50  } else if (j0>51) {
51  if(j0==0x400) return x+x; /* inf or NaN */
52  else return x; /* x is integral */
53  } else {
54  i = ((u_int32_t)(0xffffffff))>>(j0-20);
55  if((i1&i)==0) return x; /* x is integral */
56  if(huge+x>0.0) { /* raise inexact flag */
57  if(i0<0) {
58  if(j0==20) i0+=1;
59  else {
60  j = i1+(1<<(52-j0));
61  if(j<(u_int32_t)i1) i0 +=1 ; /* got a carry */
62  i1=j;
63  }
64  }
65  i1 &= (~i);
66  }
67  }
68  INSERT_WORDS(x,i0,i1);
69  return x;
70 }
GLint GLint GLint GLint GLint x
Definition: SDL_opengl.h:1574
signed int int32_t
unsigned int u_int32_t
Definition: math_private.h:31
#define EXTRACT_WORDS(ix0, ix1, d)
Definition: math_private.h:98
return Display return Display Bool Bool int int int return Display XEvent Bool(*) XPointer return Display return Display Drawable _Xconst char unsigned int unsigned int return Display Pixmap Pixmap XColor XColor unsigned int unsigned int return Display _Xconst char char int char return Display Visual unsigned int int int char unsigned int unsigned int int in j)
Definition: SDL_x11sym.h:50
#define INSERT_WORDS(d, ix0, ix1)
Definition: math_private.h:126
static const double huge
Definition: s_floor.c:27
double floor(double x)
Definition: s_floor.c:29
return Display return Display Bool Bool int int int return Display XEvent Bool(*) XPointer return Display return Display Drawable _Xconst char unsigned int unsigned int return Display Pixmap Pixmap XColor XColor unsigned int unsigned int return Display _Xconst char char int char return Display Visual unsigned int int int char unsigned int unsigned int in i)
Definition: SDL_x11sym.h:50
const GLubyte GLuint GLuint GLuint GLuint alpha GLboolean GLboolean GLboolean GLboolean alpha GLint GLint GLsizei GLsizei GLenum type GLenum GLint GLenum GLint GLint GLsizei GLsizei GLint border GLenum GLint GLint GLint GLint GLint GLsizei GLsizei height GLsizei GLsizei GLenum GLenum const GLvoid *pixels GLenum GLint i1
Definition: SDL_glfuncs.h:140
libm_hidden_def(scalbln)
Definition: s_scalbn.c:62