libmad: Add optimization config options

Configuring libmad with --enable-speed compromises accuracy and can cause audio
clipping in some cases (heard on ARM platform with some loud MP3s), so give
users the choice of MAD optimizations.

The default config corresponds to the default behavior of libmad's configure.

Signed-off-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com>

package/libmad/Config.in

@@ -6,3 +6,44 @@ config BR2_PACKAGE_LIBMAD
 	  without a floating-point unit.
 
 	  http://www.underbit.com/products/mad/
+
+if BR2_PACKAGE_LIBMAD
+
+choice
+	prompt "Speed vs. accuracy"
+	default BR2_PACKAGE_LIBMAD_OPTIMIZATION_DEFAULT
+
+config BR2_PACKAGE_LIBMAD_OPTIMIZATION_DEFAULT
+	bool "Default"
+	help
+	  Keep optimizations balanced between speed and accuracy.
+
+config BR2_PACKAGE_LIBMAD_OPTIMIZATION_SPEED
+	bool "Optimize for speed over accuracy"
+	help
+	  Compromise accuracy for speed.
+
+config BR2_PACKAGE_LIBMAD_OPTIMIZATION_ACCURACY
+	bool "Optimize for accuracy over speed"
+	help
+	  Compromise speed for accuracy.
+
+endchoice
+
+config BR2_PACKAGE_LIBMAD_SSO
+	bool "Subband synthesis optimization"
+	help
+	  Use the subband synthesis optimization, with reduced accuracy.
+
+config BR2_PACKAGE_LIBMAD_ASO
+	bool "Architecture-specific optimizations"
+	default y
+	help
+	  Use certain architecture-specific optimizations.
+
+config BR2_PACKAGE_LIBMAD_STRICT_ISO
+	bool "Strict ISO/IEC interpretations"
+	help
+	  Use strict ISO/IEC interpretations.
+
+endif

package/libmad/libmad.mk

@@ -30,6 +30,10 @@ LIBMAD_POST_INSTALL_TARGET_HOOKS += LIBMAD_INSTALL_TARGET_PC
 
 LIBMAD_CONF_OPT = \
 		--disable-debugging \
-		--enable-speed
+		$(if $(BR2_PACKAGE_LIBMAD_OPTIMIZATION_SPEED),--enable-speed) \
+		$(if $(BR2_PACKAGE_LIBMAD_OPTIMIZATION_ACCURACY),--enable-accuracy) \
+		--$(if $(BR2_PACKAGE_LIBMAD_SSO),enable,disable)-sso \
+		--$(if $(BR2_PACKAGE_LIBMAD_ASO),enable,disable)-aso \
+		--$(if $(BR2_PACKAGE_LIBMAD_STRICT_ISO),enable,disable)-strict-iso
 
 $(eval $(call AUTOTARGETS))