acinclude/ax_gcc_x86_cpuid.m4
author Sam Lantinga
Sun, 05 Apr 2020 08:58:47 -0700
changeset 13689 c3055b205671
parent 12190 04650c2fe44e
permissions -rw-r--r--
Fixed bug 5015 - SDL_RenderReadPixels on DirectX 11.1 backend seems to be broken

Konrad

It appears that I cannot use SDL_RenderReadPixels on a bound framebuffer (SDL_Texture set as render target) as it simply results in gibberish data. However, drawing that framebuffer into the default target (window surface) does render it correctly. Other backends (OpenGL, software, Direct3D) do work fine.

It looks to me like D3D11_RenderReadPixels just gets the general backbuffer and not the current render target and its backbuffer.

Here is the patch which actually fetches the current render target and its underlying ID3D11Resource which is ID3D11Texture2D.
     1 # ===========================================================================
     2 #     http://www.gnu.org/software/autoconf-archive/ax_gcc_x86_cpuid.html
     3 # ===========================================================================
     4 #
     5 # SYNOPSIS
     6 #
     7 #   AX_GCC_X86_CPUID(OP)
     8 #
     9 # DESCRIPTION
    10 #
    11 #   On Pentium and later x86 processors, with gcc or a compiler that has a
    12 #   compatible syntax for inline assembly instructions, run a small program
    13 #   that executes the cpuid instruction with input OP. This can be used to
    14 #   detect the CPU type.
    15 #
    16 #   On output, the values of the eax, ebx, ecx, and edx registers are stored
    17 #   as hexadecimal strings as "eax:ebx:ecx:edx" in the cache variable
    18 #   ax_cv_gcc_x86_cpuid_OP.
    19 #
    20 #   If the cpuid instruction fails (because you are running a
    21 #   cross-compiler, or because you are not using gcc, or because you are on
    22 #   a processor that doesn't have this instruction), ax_cv_gcc_x86_cpuid_OP
    23 #   is set to the string "unknown".
    24 #
    25 #   This macro mainly exists to be used in AX_GCC_ARCHFLAG.
    26 #
    27 # LICENSE
    28 #
    29 #   Copyright (c) 2008 Steven G. Johnson <stevenj@alum.mit.edu>
    30 #   Copyright (c) 2008 Matteo Frigo
    31 #
    32 #   This program is free software: you can redistribute it and/or modify it
    33 #   under the terms of the GNU General Public License as published by the
    34 #   Free Software Foundation, either version 3 of the License, or (at your
    35 #   option) any later version.
    36 #
    37 #   This program is distributed in the hope that it will be useful, but
    38 #   WITHOUT ANY WARRANTY; without even the implied warranty of
    39 #   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
    40 #   Public License for more details.
    41 #
    42 #   You should have received a copy of the GNU General Public License along
    43 #   with this program. If not, see <http://www.gnu.org/licenses/>.
    44 #
    45 #   As a special exception, the respective Autoconf Macro's copyright owner
    46 #   gives unlimited permission to copy, distribute and modify the configure
    47 #   scripts that are the output of Autoconf when processing the Macro. You
    48 #   need not follow the terms of the GNU General Public License when using
    49 #   or distributing such scripts, even though portions of the text of the
    50 #   Macro appear in them. The GNU General Public License (GPL) does govern
    51 #   all other use of the material that constitutes the Autoconf Macro.
    52 #
    53 #   This special exception to the GPL applies to versions of the Autoconf
    54 #   Macro released by the Autoconf Archive. When you make and distribute a
    55 #   modified version of the Autoconf Macro, you may extend this special
    56 #   exception to the GPL to apply to your modified version as well.
    57 
    58 #serial 7
    59 
    60 AC_DEFUN([AX_GCC_X86_CPUID],
    61 [AC_REQUIRE([AC_PROG_CC])
    62 AC_LANG_PUSH([C])
    63 AC_CACHE_CHECK(for x86 cpuid $1 output, ax_cv_gcc_x86_cpuid_$1,
    64  [AC_RUN_IFELSE([AC_LANG_PROGRAM([#include <stdio.h>], [
    65      int op = $1, eax, ebx, ecx, edx;
    66      FILE *f;
    67       __asm__("cpuid"
    68         : "=a" (eax), "=b" (ebx), "=c" (ecx), "=d" (edx)
    69         : "a" (op));
    70      f = fopen("conftest_cpuid", "w"); if (!f) return 1;
    71      fprintf(f, "%x:%x:%x:%x\n", eax, ebx, ecx, edx);
    72      fclose(f);
    73      return 0;
    74 ])],
    75      [ax_cv_gcc_x86_cpuid_$1=`cat conftest_cpuid`; rm -f conftest_cpuid],
    76      [ax_cv_gcc_x86_cpuid_$1=unknown; rm -f conftest_cpuid],
    77      [ax_cv_gcc_x86_cpuid_$1=unknown])])
    78 AC_LANG_POP([C])
    79 ])