src/libm/s_scalbn.c
author Ryan C. Gordon <icculus@icculus.org>
Thu, 09 Apr 2015 22:28:37 -0400
changeset 9541 cf8fab52e33b
parent 7678 286c42d7c5ed
child 11683 48bcba563d9c
permissions -rw-r--r--
Merged Alex Szpakowski's iOS-improvement branch to default.

Fixes Bugzilla #2798.
Fixes Bugzilla #2212.
Fixes Bugzilla #2826.
Fixes Bugzilla #2661.
Fixes Bugzilla #1885.
Fixes Bugzilla #1578.
Fixes Bugzilla #2751.

(whew!)

Notable changes, from Alex's notes:

- The SDL_WINDOW_ALLOW_HIGHDPI flag is now needed (along with SDL_GL_GetDrawableSize or SDL_GetRendererOutputSize) to use Retina / high DPI resolutions, bringing SDL’s Retina-related behavior on iOS in line with Mac OS X. Window dimensions and display modes are now in the “points” (non-high DPI) coordinate system rather than pixels, whereas SDL_GL_GetDrawableSize is in pixels.

- Reworked the custom extended launch screen code:
- It now hides after the first SDL_PumpEvents call rather than SDL_CreateWindow, and it fades out in a similar manner to the system launch screen behavior.
- It now mirrors the system launch screen behavior when deciding which image to display: it falls back to using the Launch Images dictionary in Info.plist if the iOS 8+ launch screen nib isn’t available, and if the Launch Images dictionary doesn’t exist it uses the old standard launch image names.
- The extended launch screen can now be disabled via the SDL_IPHONE_LAUNCHSCREEN define in SDL_config_iphoneos.h.

- Added support for SDL_HINT_ACCELEROMETER_AS_JOYSTICK.

- Added access to a window view's renderbuffer and framebuffer to syswm.

- Added OpenGL ES debug labels for the Renderbuffer and Framebuffer Objects created with SDL_GL_CreateContext.

- Added support for sRGB OpenGL ES contexts on iOS 7+.

- Updated OpenGL ES contexts to support native-resolution rendering (when SDL_WINDOW_ALLOW_HIGHDPI is enabled) on the iPhone 6 Plus, i.e. 1080x1920 rather than 1242x2208.

- Updated SDL_GL_CreateContext, SDL_GL_SwapWindow, SDL_GL_MakeCurrent, and SDL_GL_DeleteContext to be more robust.

- Updated SDL windows to display a UIView at all times, even when an OpenGL context is not active. This allows rotation, touch events, and other windowing-related events to work properly without an active OpenGL context. It also makes it easier to use SDL_GetWindowWMInfo after creating a SDL window.

- Updated the iOS-specific Objective-C code to use cleaner and more modern language features and APIs, including ARC instead of manual reference counting.

- Updated SDL_HINT_ORIENTATIONS to allow disabling custom orientations if the hint is set with no valid orientation names.

- Fixed several rotation and orientation bugs with windows and display modes, especially in iOS 8+.

- Fixed SDL_SetWindowFullscreen failing to update the status bar visibility on iOS 7+.

- Fixed the orientation of the offset applied to the window’s view when the onscreen keyboard is shown in iOS 8+.

- Fixed SDL_IsScreenKeyboardShown (patch by Phil Hassey.)

- Fixed several major memory leaks caused by missing autorelease pool blocks in the iOS-specific Objective-C code.

- Removed several dead code paths.

- The iOS 7 SDK (Xcode 5) or newer is now required to build SDL for iOS.
     1 /* @(#)s_scalbn.c 5.1 93/09/24 */
     2 /*
     3  * ====================================================
     4  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
     5  *
     6  * Developed at SunPro, a Sun Microsystems, Inc. business.
     7  * Permission to use, copy, modify, and distribute this
     8  * software is freely granted, provided that this notice
     9  * is preserved.
    10  * ====================================================
    11  */
    12 
    13 #if defined(LIBM_SCCS) && !defined(lint)
    14 static const char rcsid[] =
    15     "$NetBSD: s_scalbn.c,v 1.8 1995/05/10 20:48:08 jtc Exp $";
    16 #endif
    17 
    18 /*
    19  * scalbn (double x, int n)
    20  * scalbn(x,n) returns x* 2**n  computed by  exponent
    21  * manipulation rather than by actually performing an
    22  * exponentiation or a multiplication.
    23  */
    24 
    25 #include "math_libm.h"
    26 #include "math_private.h"
    27 
    28 libm_hidden_proto(copysign)
    29 #ifdef __STDC__
    30      static const double
    31 #else
    32      static double
    33 #endif
    34        two54 = 1.80143985094819840000e+16,      /* 0x43500000, 0x00000000 */
    35          twom54 = 5.55111512312578270212e-17,   /* 0x3C900000, 0x00000000 */
    36          huge_val = 1.0e+300, tiny = 1.0e-300;
    37 
    38 libm_hidden_proto(scalbn)
    39 #ifdef __STDC__
    40      double scalbn(double x, int n)
    41 #else
    42      double scalbn(x, n)
    43      double x;
    44      int n;
    45 #endif
    46 {
    47     int32_t k, hx, lx;
    48     EXTRACT_WORDS(hx, lx, x);
    49     k = (hx & 0x7ff00000) >> 20;        /* extract exponent */
    50     if (k == 0) {               /* 0 or subnormal x */
    51         if ((lx | (hx & 0x7fffffff)) == 0)
    52             return x;           /* +-0 */
    53         x *= two54;
    54         GET_HIGH_WORD(hx, x);
    55         k = ((hx & 0x7ff00000) >> 20) - 54;
    56         if (n < -50000)
    57             return tiny * x;    /* underflow */
    58     }
    59     if (k == 0x7ff)
    60         return x + x;           /* NaN or Inf */
    61     k = k + n;
    62     if (k > 0x7fe)
    63         return huge_val * copysign(huge_val, x);        /* overflow  */
    64     if (k > 0) {                /* normal result */
    65         SET_HIGH_WORD(x, (hx & 0x800fffff) | (k << 20));
    66         return x;
    67     }
    68     if (k <= -54) {
    69         if (n > 50000)          /* in case integer overflow in n+k */
    70             return huge_val * copysign(huge_val, x);    /* overflow */
    71         else
    72             return tiny * copysign(tiny, x);    /* underflow */
    73     }
    74     k += 54;                    /* subnormal result */
    75     SET_HIGH_WORD(x, (hx & 0x800fffff) | (k << 20));
    76     return x * twom54;
    77 }
    78 
    79 libm_hidden_def(scalbn)