From 17dfaa3aaef28f38b27c5d797be0a938c4ca38e2 Mon Sep 17 00:00:00 2001
From: Chris Robinson <chris.kcat@gmail.com>
Date: Mon, 13 Aug 2012 10:37:49 -0700
Subject: [PATCH] Add a config option to disable use of CPU extensions

---
 Alc/ALc.c                 | 32 +++++++++++++++++++++++++++++++-
 Alc/helpers.c             | 19 +++++++++++--------
 OpenAL32/Include/alMain.h |  4 +++-
 alsoftrc.sample           |  7 +++++++
 4 files changed, 52 insertions(+), 10 deletions(-)

diff --git a/Alc/ALc.c b/Alc/ALc.c
index b017c480..e664d25a 100644
--- a/Alc/ALc.c
+++ b/Alc/ALc.c
@@ -769,6 +769,7 @@ static void alc_init(void)
 static void alc_initconfig(void)
 {
     const char *devs, *str;
+    ALuint capfilter;
     float valf;
     int i, n;
 
@@ -790,7 +791,36 @@ static void alc_initconfig(void)
 
     ReadALConfig();
 
-    FillCPUCaps();
+    capfilter = CPU_CAP_ALL;
+    if(ConfigValueStr(NULL, "disable-cpu-exts", &str))
+    {
+        if(strcasecmp(str, "all") == 0)
+            capfilter = 0;
+        else
+        {
+            size_t len;
+            const char *next = str;
+
+            i = 0;
+            do {
+                str = next;
+                next = strchr(str, ',');
+
+                while(isspace(str[0]))
+                    str++;
+                if(!str[0] || str[0] == ',')
+                    continue;
+
+                len = (next ? ((size_t)(next-str)) : strlen(str));
+                if(strncasecmp(str, "neon", len) == 0)
+                    capfilter &= ~CPU_CAP_NEON;
+                else
+                    WARN("Invalid CPU extension \"%s\"\n", str);
+            } while(next++);
+        }
+    }
+    FillCPUCaps(capfilter);
+
     InitHrtf();
 
 #ifdef _WIN32
diff --git a/Alc/helpers.c b/Alc/helpers.c
index 6051573e..d963f3a8 100644
--- a/Alc/helpers.c
+++ b/Alc/helpers.c
@@ -63,8 +63,10 @@ DEFINE_DEVPROPKEY(DEVPKEY_Device_FriendlyName, 0xa45c254e, 0xdf1c, 0x4efd, 0x80,
 ALuint CPUCapFlags = 0;
 
 
-void FillCPUCaps(void)
+void FillCPUCaps(ALuint capfilter)
 {
+    ALuint caps = 0;
+
 #if defined(__i386__) || defined(__x86_64__) || defined(_M_IX86) || defined(_M_X64)
 /* FIXME: We really should get this for all available CPUs in case different
  * CPUs have different caps (is that possible on one machine?). */
@@ -90,11 +92,11 @@ void FillCPUCaps(void)
         {
 #ifdef bit_MMX
             if((cpuinf[0].regs[3]&bit_MMX))
-                CPUCapFlags |= CPU_CAP_MMX;
+                caps |= CPU_CAP_MMX;
 #endif
 #ifdef bit_SSE
             if((cpuinf[0].regs[3]&bit_SSE))
-                CPUCapFlags |= CPU_CAP_SSE;
+                caps |= CPU_CAP_SSE;
 #endif
         }
     }
@@ -102,13 +104,14 @@ void FillCPUCaps(void)
 #endif
 #ifdef HAVE_ARM_NEON_H
     /* Assume Neon support if compiled with it */
-    CPUCapFlags |= CPU_CAP_NEON;
+    caps |= CPU_CAP_NEON;
 #endif
 
-    TRACE("Got caps:%s%s%s%s\n", ((CPUCapFlags&CPU_CAP_MMX)?" MMX":""),
-                                 ((CPUCapFlags&CPU_CAP_SSE)?" SSE":""),
-                                 ((CPUCapFlags&CPU_CAP_NEON)?" Neon":""),
-                                 ((!CPUCapFlags)?" (none)":""));
+    TRACE("Got caps:%s%s%s%s\n", ((caps&CPU_CAP_MMX)?((capfilter&CPU_CAP_MMX)?" MMX":" (MMX)"):""),
+                                 ((caps&CPU_CAP_SSE)?((capfilter&CPU_CAP_SSE)?" SSE":" (SSE)"):""),
+                                 ((caps&CPU_CAP_NEON)?((capfilter&CPU_CAP_NEON)?" Neon":" (Neon)"):""),
+                                 ((!caps)?" (none)":""));
+    CPUCapFlags = caps & capfilter;
 }
 
 
diff --git a/OpenAL32/Include/alMain.h b/OpenAL32/Include/alMain.h
index 1f73ad72..f05d7316 100644
--- a/OpenAL32/Include/alMain.h
+++ b/OpenAL32/Include/alMain.h
@@ -768,9 +768,11 @@ enum {
     CPU_CAP_MMX    = 1<<0,
     CPU_CAP_SSE    = 1<<1,
     CPU_CAP_NEON   = 1<<3,
+
+    CPU_CAP_ALL = CPU_CAP_MMX|CPU_CAP_SSE|CPU_CAP_NEON
 };
 
-void FillCPUCaps(void);
+void FillCPUCaps(ALuint capfilter);
 
 
 /**
diff --git a/alsoftrc.sample b/alsoftrc.sample
index 58746c8f..affcc2fa 100644
--- a/alsoftrc.sample
+++ b/alsoftrc.sample
@@ -11,6 +11,13 @@
 # possible). Note: options that are left unset may default to app- or system-
 # specified values. These are the current available settings:
 
+## disable-cpu-exts:
+#  Disables use of the listed CPU extensions. Certain methods may utilize CPU
+#  extensions when detected, and this option is useful for preventing those
+#  extensions from being used. The available extensions are: neon. Specifying
+#  'all' disables use of all extensions.
+#disable-cpu-exts =
+
 ## channels:
 #  Sets the output channel configuration. If left unspecified, one will try to
 #  be detected from the system, and defaulting to stereo. The available values
-- 
2.11.4.GIT