Merge pull request #49 from larry-xmos/MAINTEN/v0.1

Apply host directory move in DFU documentation too

CHANGELOG.rst

@@ -1,6 +1,15 @@
 lib_xua Change Log
 ==================
 
+0.1.2
+-----
+
+  * ADDED:     Application note AN00246
+  * RESOLVED:  Runtime exception issues when incorrect feedback calculated
+    (introduced in sc_xud 6.13)
+  * RESOLVED:  Output sample counter reset on stream start. Caused playback
+    issues on some Linux based hosts
+
 0.1.1
 -----
 

doc_dfu/Makefile

@@ -1 +1 @@
-SOURCE_INCLUDE_DIRS=../host/xmosdfu
+SOURCE_INCLUDE_DIRS=../lib_xua/host/xmosdfu

doc_dfu/building_xmos_dfu.rst

@@ -4,7 +4,7 @@ Building the XMOS DFU loader - macOS
 ====================================
 
 The XMOS DFU loader is provided as source as part of the USB Audio
-framework, located in sc_usb_audio/module_dfu/host/xmos_dfu_osx.
+framework, located in lib_xua/host/xmosdfu.
 
 The loader is compiled using libusb, the code for the loader is contained in the
 file ``xmosdfu.cpp``

examples/AN00246_xua_example/Makefile

@@ -3,13 +3,14 @@ APP_NAME = app_xua_simple
 TARGET = xk-audio-216-mc.xn
 
 # The flags passed to xcc when building the application
-XCC_FLAGS     = -fcomment-asm -Xmapper --map -Xmapper MAPFILE -O3 -report -fsubword-select -save-temps -g -Wno-unused-function -Wno-timing -DXUD_SERIES_SUPPORT=XUD_X200_SERIES -DUSB_TILE=tile[1] -DSDA_HIGH=2 -DSCL_HIGH=1 
+XCC_FLAGS	= -fcomment-asm -Xmapper --map -Xmapper MAPFILE -O3 -report -fsubword-select -save-temps \
+			  -g -Wno-unused-function -Wno-timing -DXUD_SERIES_SUPPORT=XUD_X200_SERIES -DUSB_TILE=tile[1] \
+			  -DSDA_HIGH=2 -DSCL_HIGH=1 -fxscope
 
 # The USED_MODULES variable lists other module used by the application. These
 # modules will extend the SOURCE_DIRS, INCLUDE_DIRS and LIB_DIRS variables.
 # Modules are expected to be in the directory above the BASE_DIR directory.
-USED_MODULES = lib_mic_array lib_logging lib_xua lib_device_control lib_xud module_i2c_shared module_i2c_single_port module_locks
+USED_MODULES = lib_xua lib_device_control lib_xud module_i2c_shared module_i2c_single_port module_locks
-
 
 #=============================================================================
 # The following part of the Makefile includes the common build infrastructure

examples/AN00246_xua_example/README.rst

@@ -0,0 +1,34 @@
+
+How to use the lib_xua_library
+===============================
+
+.. version:: 0.1.0
+
+Summary
+-------
+
+Required tools and libraries
+............................
+
+.. appdeps::
+
+Required hardware
+.................
+
+The example code provided with the application has been implemented
+and tested on the xCORE-200 Multi-channel Audio Board
+
+Prerequisites
+.............
+
+ * This document assumes familiarity with the XMOS xCORE architecture,
+   the XMOS tool chain and the xC language. Documentation related to these
+   aspects which are not specific to this application note are linked to in
+   the references appendix.
+
+ * For a description of XMOS related terms found in this document
+   please see the XMOS Glossary [#]_.
+
+.. [#] http://www.xmos.com/published/glossary
+
+

examples/AN00246_xua_example/doc/AN00246.rst

@@ -0,0 +1,240 @@
+.. include:: ../../README.rst
+
+|newpage|
+
+Overview
+--------
+
+Introduction
+............
+
+The XMOS USB Audio (XUA) library provides an implemention of USB Audio Class 2.0 
+
+This application note demonstrates the implementation of a basic USB Audio Device on 
+the xCORE-200 MC Audio board.
+
+Block diagram
+.............
+
+.. figure:: images/block_diagram.*
+   :width: 80%
+
+   Application block diagram
+
+The application uses a single logical core which runs the application and makes
+calls to the |I2C| master library functions as required.
+
+How to use lib_xua
+------------------
+
+The Makefile
+............
+
+To start using the lib_xua, you need to add ``lib_xua`` to your Makefile::
+
+  USED_MODULES = .. lib_xua ...
+
+This demo also uses the XMOS USB Device library (``lib_xud``) for low-level USB connectivity.
+The Makefile also includes::
+
+  USED_MODULES = .. lib_xud ..
+
+``lib_xud`` library requires some flags for correct operation. Firstly the 
+tile on which ``lib_xud`` will be execute, for example::
+
+    XCC_FLAGS = .. -DUSB_TILE=tile[1] ..
+
+Secondly, the architecture of the target device, for example::
+
+  XCC_FLAGS = .. -DXUD_SERIES_SUPPORT=XUD_X200_SERIES ..
+
+Includes
+........
+
+This application requires the system header that defines XMOS xCORE specific
+defines for declaring and initialising hardware:
+
+.. literalinclude:: app_xua_simple.xc
+   :start-on: include <xs1.h>
+   :end-before: include "xua.h"
+
+The XUA library functions are defined in ``xua.h``. This header must
+be included in your code to use the library. 
+
+.. literalinclude:: app_xua_simple.xc
+   :start-on: include "xua.h"
+   :end-on: include "xud_device.h"
+
+Allocating hardware resources
+.............................
+
+A most basic implementation of a USB Audio device (i.e. simple stereo input and output via I2S)
+using ``lib_xua`` requires the follow pins:
+
+    - I2S Bit Clock (from xCORE to DAC)
+    - I2S L/R clock (from xCORE to DAC)
+    - I2S Data line (from xCORE to DAC)
+    - I2S Data line (from ADC to xCORE)
+    - Audio Master clock (from clock source to xCORE)
+
+.. note::
+
+    ANOO246 assumes xCORE is I2S bus master
+
+On an xCORE the pins are controlled by ``ports``. The application therefore declares various ``ports``
+for this purpose:
+
+.. literalinclude:: app_xua_simple.xc
+   :start-on: /* Port declaration
+   :end-on: /* Clock-block
+
+In addition to ``port`` resources two clock-block resources are also required:
+
+.. literalinclude:: app_xua_simple.xc
+   :start-on: /* Clock-block
+   :end-on: /* clock clk_audio_mclk
+
+Other declarations
+..................
+
+``lib_xua`` currently requires the manual declaration of tables for the endpoint types for
+``lib_xud`` and the calling the main XUD funtion in a par (``XUD_Main()``).
+
+For a simple application the following endpoints are required:
+
+    - ``Control`` enpoint zero 
+    - ``Isochonous`` endpoint for each direction for audio data to/from the USB host
+
+These are declared as follows:
+
+.. literalinclude:: app_xua_simple.xc
+   :start-on: /* Endpoint type tables
+   :end-on: /* XUD_EpType epTypeTableIn
+
+The application main() function
+...............................
+
+The ``main()`` function sets up the tasks in the application.
+
+Various channels are required in order to allow the required tasks to communcate. 
+These must be declared":
+
+.. literalinclude:: app_xua_simple.xc
+   :start-on: /* Channels for lib_xud
+   :end-on: /* chan c_aud_ctl
+
+The rest of the ``main()`` function starts all the tasks in parallel
+using the xC ``par`` construct:
+
+.. literalinclude:: app_xua_simple.xc
+   :start-on: par
+   :end-before: return 0
+
+This code starts the low-level USB task, an Endpoint 0 task, an Audio buffering task and a task to handle 
+the audio I/O (i.e. I2S signalling).
+
+Configuration 
+.............
+
+``lib_xua`` has many parameters than can be configured at build time, some examples include:
+
+    - Sample-rates
+    - Channel counts
+    - Audio Class version
+    - Product/Vendor ID's
+    - Various product strings
+    - Master clock frequency
+
+These parameters are set via defines in an optional ``xua_conf.h`` header file.
+
+|appendix|
+|newpage|
+
+Demo Hardware Setup
+-------------------
+
+To run the demo, connect a USB cable to power the xCORE-200 MC Audio board 
+and plug the xTAG to the board and connect the xTAG USB cable to your
+development machine.
+
+.. figure:: images/hw_setup.*
+   :width: 80%
+
+   Hardware setup
+
+|newpage|
+
+Launching the demo application
+------------------------------
+
+Once the demo example has been built either from the command line using xmake or
+via the build mechanism of xTIMEcomposer studio it can be executed on the xCORE-200
+MC Audio board.
+
+Once built there will be a ``bin/`` directory within the project which contains
+the binary for the xCORE device. The xCORE binary has a XMOS standard .xe extension.
+
+Launching from the command line
+...............................
+
+From the command line you use the ``xrun`` tool to download and run the code
+on the xCORE device::
+
+  xrun --xscope bin/app_xua_simple.xe
+
+Once this command has executed the application will be running on the
+xCORE-200 MC Audio Board
+
+Launching from xTIMEcomposer Studio
+...................................
+
+From xTIMEcomposer Studio use the run mechanism to download code to xCORE device.
+Select the xCORE binary from the ``bin/`` directory, right click and go to Run
+Configurations. Double click on xCORE application to create a new run configuration,
+enable the xSCOPE I/O mode in the dialog box and then
+select Run.
+
+Once this command has executed the application will be running on the
+xCORE-200 MC Audio board.
+
+Running the application
+.......................
+
+Once running the device will be detected as a USB Audio device - note, Windows operating 
+systems may require a third party driver for correct operation 
+
+|newpage|
+
+References
+----------
+
+.. nopoints::
+
+  * XMOS Tools User Guide
+
+    http://www.xmos.com/published/xtimecomposer-user-guide
+
+  * XMOS xCORE Programming Guide
+
+    http://www.xmos.com/published/xmos-programming-guide
+
+  * XMOS lib_xua Library
+
+    http://www.xmos.com/support/libraries/lib_xua
+    
+  * XMOS lib_xud Library
+
+    http://www.xmos.com/support/libraries/lib_xud
+
+|newpage|
+
+Full source code listing
+------------------------
+
+Source code for main.xc
+.......................
+
+.. literalinclude:: app_xua_simple.xc
+  :largelisting:
+
+|newpage|

examples/AN00246_xua_example/doc/rst/AN00246.rst

@@ -0,0 +1,229 @@
+.. include:: ../../README.rst
+
+|newpage|
+
+Overview
+--------
+
+Introduction
+............
+
+The XMOS USB Audio (XUA) library provides an implemention of USB Audio Class 2.0 
+
+This application note demonstrates the implementation of a basic USB Audio Device on 
+the xCORE-200 MC Audio board.
+
+Block diagram
+.............
+
+.. figure:: images/block_diagram.*
+   :width: 80%
+
+   Application block diagram
+
+The application uses a single logical core which runs the application and makes
+calls to the |I2C| master library functions as required.
+
+How to use lib_xua
+------------------
+
+The Makefile
+............
+
+To start using the lib_xua, you need to add ``lib_xua`` to your Makefile::
+
+  USED_MODULES = .. lib_xua ...
+
+This demo also uses the XMOS USB Device library (``lib_xud``) for low-level USB connectivity.
+The Makefile also includes::
+
+  USED_MODULES = .. lib_xud ..
+
+``lib_xud`` library requires some flags for correct operation. Firstly the 
+tile on which ``lib_xud`` will be execute, for example::
+
+    XCC_FLAGS = .. -DUSB_TILE=tile[1] ..
+
+Secondly, the architecture of the target device, for example::
+
+  XCC_FLAGS = .. -DXUD_SERIES_SUPPORT=XUD_X200_SERIES ..
+
+Includes
+........
+
+This application requires the system header that defines XMOS xCORE specific
+defines for declaring and initialising hardware:
+
+.. literalinclude:: app_xua_simple.xc
+   :start-on: include <xs1.h>
+   :end-before: include "xua.h"
+
+The XUA library functions are defined in ``xua.h``. This header must
+be included in your code to use the library. 
+
+.. literalinclude:: app_xua_simple.xc
+   :start-on: include "xua.h"
+   :end-on: include "xud_device.h"
+
+Allocating hardware resources
+.............................
+
+A most basic implementation of a USB Audio device (i.e. simple stereo input and output via I2S)
+using ``lib_xua`` requires the follow pins:
+
+    - I2S Bit Clock (from xCORE to DAC)
+    - I2S L/R clock (from xCORE to DAC)
+    - I2S Data line (from xCORE to DAC)
+    - I2S Data line (from ADC to xCORE)
+    - Audio Master clock (from clock source to xCORE)
+
+.. note::
+
+    ANOO246 assumes xCORE is I2S bus master
+
+On an xCORE the pins are controlled by ``ports``. The application therefore declares various ``ports``
+for this purpose:
+
+.. literalinclude:: app_xua_simple.xc
+   :start-on: /* Port declaration
+   :end-on: /* Clock-block
+
+In addition to ``port`` resources two clock-block resources are also required:
+
+.. literalinclude:: app_xua_simple.xc
+   :start-on: /* Clock-block
+   :end-on: /* clock clk_audio_mclk
+
+Other declarations
+..................
+
+``lib_xua`` currently requires the manual declaration of tables for the endpoint types for
+``lib_xud`` and the calling the main XUD funtion in a par (``XUD_Main()``).
+
+For a simple application the following endpoints are required:
+
+    - ``Control`` enpoint zero 
+    - ``Isochonous`` endpoint for each direction for audio data to/from the USB host
+
+These are declared as follows:
+
+.. literalinclude:: app_xua_simple.xc
+   :start-on: /* Endpoint type tables
+   :end-on: /* XUD_EpType epTypeTableIn
+
+The application main() function
+...............................
+
+The ``main()`` function sets up the tasks in the application.
+
+Various channels are required in order to allow the required tasks to communcate. 
+These must be declared":
+
+.. literalinclude:: app_xua_simple.xc
+   :start-on: /* Channels for lib_xud
+   :end-on: /* chan c_aud_ctl
+
+The rest of the ``main()`` function starts all the tasks in parallel
+using the xC ``par`` construct:
+
+.. literalinclude:: app_xua_simple.xc
+   :start-on: par
+   :end-before: return 0
+
+This code starts the low-level USB task, an Endpoint 0 task, an Audio buffering task and a task to handle 
+the audio I/O (i.e. I2S signalling).
+
+Configuration 
+.............
+
+|appendix|
+|newpage|
+
+Demo Hardware Setup
+-------------------
+
+To run the demo, connect a USB cable to power the xCORE-200 MC Audio board 
+and plug the xTAG to the board and connect the xTAG USB cable to your
+development machine.
+
+.. figure:: images/hw_setup.*
+   :width: 80%
+
+   Hardware setup
+
+|newpage|
+
+Launching the demo application
+------------------------------
+
+Once the demo example has been built either from the command line using xmake or
+via the build mechanism of xTIMEcomposer studio it can be executed on the xCORE-200
+MC Audio board.
+
+Once built there will be a ``bin/`` directory within the project which contains
+the binary for the xCORE device. The xCORE binary has a XMOS standard .xe extension.
+
+Launching from the command line
+...............................
+
+From the command line you use the ``xrun`` tool to download and run the code
+on the xCORE device::
+
+  xrun --xscope bin/app_xua_simple.xe
+
+Once this command has executed the application will be running on the
+xCORE-200 MC Audio Board
+
+Launching from xTIMEcomposer Studio
+...................................
+
+From xTIMEcomposer Studio use the run mechanism to download code to xCORE device.
+Select the xCORE binary from the ``bin/`` directory, right click and go to Run
+Configurations. Double click on xCORE application to create a new run configuration,
+enable the xSCOPE I/O mode in the dialog box and then
+select Run.
+
+Once this command has executed the application will be running on the
+xCORE-200 MC Audio board.
+
+Running the application
+.......................
+
+Once running the device will be detected as a USB Audio device - note, Windows operating 
+systems may require a third party driver for correct operation 
+
+|newpage|
+
+References
+----------
+
+.. nopoints::
+
+  * XMOS Tools User Guide
+
+    http://www.xmos.com/published/xtimecomposer-user-guide
+
+  * XMOS xCORE Programming Guide
+
+    http://www.xmos.com/published/xmos-programming-guide
+
+  * XMOS lib_xua Library
+
+    http://www.xmos.com/support/libraries/lib_xua
+    
+  * XMOS lib_xud Library
+
+    http://www.xmos.com/support/libraries/lib_xud
+
+|newpage|
+
+Full source code listing
+------------------------
+
+Source code for main.xc
+.......................
+
+.. literalinclude:: app_xua_simple.xc
+  :largelisting:
+
+|newpage|

examples/AN00246_xua_example/doc/rst/xdoc.conf

@@ -0,0 +1,2 @@
+XMOSNEWSTYLE=1
+SOURCE_INCLUDE_DIRS=../../src

examples/AN00246_xua_example/src/app_xua_simple.xc

@@ -13,8 +13,8 @@
 #include <xs1.h>
 #include <platform.h>
 
-#include "xud_device.h"
 #include "xua.h"
+#include "xud_device.h"
 
 /* Port declarations. Note, the defines come from the xn file */
 buffered out port:32 p_i2s_dac[]    = {PORT_I2S_DAC0};   /* I2S Data-line(s) */
@@ -33,10 +33,12 @@ unsafe
 }
 
 in port p_for_mclk_count            = PORT_MCLK_COUNT;   /* Extra port for counting master clock ticks */
+in port p_mclk_in2                  = PORT_MCLK_IN2;
 
 /* Clock-block declarations */
 clock clk_audio_bclk                = on tile[0]: XS1_CLKBLK_4;   /* Bit clock */    
 clock clk_audio_mclk                = on tile[0]: XS1_CLKBLK_5;   /* Master clock */
+clock clk_audio_mclk2               = on tile[1]: XS1_CLKBLK_1;   /* Master clock */
 
 /* Endpoint type tables - informs XUD what the transfer types for each Endpoint in use and also
  * if the endpoint wishes to be informed of USB bus resets */
@@ -55,7 +57,7 @@ int main()
     /* Channel for audio data between buffering cores and audio IO core */
     chan c_aud;
     
-    /* Channel for communcating control messages from EP0 to the rest of the device (via the buffering cores */
+    /* Channel for communicating control messages from EP0 to the rest of the device (via the buffering cores */
     chan c_aud_ctl;
 
     par
@@ -63,7 +65,6 @@ int main()
         /* Low level USB device layer core */ 
         on tile[1]: XUD_Main(c_ep_out, 2, c_ep_in, 2,
                       c_sof, epTypeTableOut, epTypeTableIn, 
-                      /* TODO rm me! */
                       null, null, -1 , 
                       XUD_SPEED_HS, XUD_PWR_BUS);
         
@@ -73,7 +74,14 @@ int main()
 
         /* Buffering cores - handles audio data to/from EP's and gives/gets data to/from the audio I/O core */
         /* Note, this spawns two cores */
-        on tile[1]: XUA_Buffer(c_ep_out[1], c_ep_in[1], c_sof, c_aud_ctl, p_for_mclk_count, c_aud);
+        on tile[1]: {
+                        set_clock_src(clk_audio_mclk2, p_mclk_in2);
+                        set_port_clock(p_for_mclk_count, clk_audio_mclk2);
+                        start_clock(clk_audio_mclk2);
+
+                        XUA_Buffer(c_ep_out[1], c_ep_in[1], c_sof, c_aud_ctl, p_for_mclk_count, c_aud);
+
+                    }
 
         /* IOHub core does most of the audio IO i.e. I2S (also serves as a hub for all audio) */
         on tile[0]: {

examples/AN00246_xua_example/src/xua_conf.h

@@ -10,10 +10,6 @@
 #define MAX_FREQ 48000
 
 #define EXCLUDE_USB_AUDIO_MAIN
-#define NUM_PDM_MICS 0
-#define XUD_TILE 1
-#define AUDIO_IO_TILE 0
-#define MIXER 0
 
 #define SPDIF_TX_INDEX 0
 #define VENDOR_STR "XMOS"
@@ -26,6 +22,3 @@
 #define AUDIO_CLASS_FALLBACK 0
 #define BCD_DEVICE 0x1234
 #define XUA_DFU_EN 0
-
-/* TODO */
-#define XUA_DFU XUA_DFU_EN

lib_xua/host/xmosdfu/xmosdfu.cpp

@@ -18,9 +18,7 @@ device_pid_t pidList[] = {
     { "XMOS_L1_AUDIO1_PID",          0x0003},
     { "XMOS_L2_AUDIO2_PID",          0x0004},
     { "XMOS_SU1_AUDIO2_PID",         0x0008},
-    { "XMOS_U8_MFA_AUDIO2_PID",      0x000A},
+    { "XMOS_U8_MFA_AUDIO2_PID",      0x000A}
-    { "XMOS_VF_SPK_BASE_AUDIO2_PID",         0x0010},
-    { "XMOS_VF_SPK_BASE_AUDIO1_PID",         0x0011}
 };
 
 unsigned int XMOS_DFU_IF = 0;

lib_xua/module_build_info

@@ -13,10 +13,13 @@ MODULE_XCC_FLAGS = $(XCC_FLAGS) -O3 -DREF_CLK_FREQ=100 -fasm-linenum -fcomment-a
 
 OPTIONAL_HEADERS += xua_conf.h
 
-VERSION = 0.1.1
+VERSION = 0.1.2
 
 DEPENDENT_MODULES = lib_logging(>=2.1.0) lib_xud(>=0.1.0)
 
+#ignore host dir
+SOURCE_DIRS = src/*
+
 #core
 EXCLUDE_FILES += descriptors_2.rst
 XCC_FLAGS_xua_endpoint0.c = -Os -mno-dual-issue $(XCC_FLAGS)

lib_xua/src/core/buffer/decouple/decouple.xc

@@ -491,12 +491,12 @@ __builtin_unreachable();
             totalSampsToWrite = speedRem >> 16;
             speedRem &= 0xffff;
 
-# if 0
+            /* This patches up the case where the FB is well off, leading to totalSampsToWrite to also be off */
+            /* This can be startup case, bad mclk input etc */
             if (totalSampsToWrite < 0 || totalSampsToWrite * g_curSubSlot_In * g_numUsbChan_In > g_maxPacketSize)
             {
                 totalSampsToWrite = 0;
             }
-#endif
 
             /* Calc slots left in fifo */
             space_left = g_aud_to_host_rdptr - g_aud_to_host_wrptr;
@@ -507,7 +507,6 @@ __builtin_unreachable();
                 space_left = aud_to_host_fifo_end - g_aud_to_host_wrptr;
             }
 
-            //if((space_left > 0) && (space_left < (totalSampsToWrite * g_numUsbChan_In * g_curSubSlot_In + 4)))
             if((space_left < (totalSampsToWrite * g_numUsbChan_In * g_curSubSlot_In + 4)))
             {
                 /* In pipe has filled its buffer - we need to overflow
@@ -567,7 +566,6 @@ __builtin_unreachable();
 
         outUnderflow = (g_aud_from_host_rdptr == g_aud_from_host_wrptr);
 
-
         if (!outUnderflow)
         {
             read_via_xc_ptr(aud_data_remaining_to_device, g_aud_from_host_rdptr);
@@ -595,6 +593,7 @@ static inline void SetupZerosSendBuffer(XUD_ep aud_to_host_usb_ep, unsigned samp
     asm volatile("stw %0, %1[0]"::"r"(mid),"r"(g_aud_to_host_zeros));
 
 #if XUA_DEBUG_BUFFER
+    printstr("SetupZerosSendBuffer\n");
     printstr("slotSize: ");
     printintln(slotSize);
     printstr("g_numUsbChan_In: ");
@@ -613,10 +612,6 @@ static inline void SetupZerosSendBuffer(XUD_ep aud_to_host_usb_ep, unsigned samp
     XUD_SetReady_InPtr(aud_to_host_usb_ep, p+4, mid);
 }
 
-
-
-unsigned char tmpBuffer[1026];
-
 #pragma unsafe arrays
 void XUA_Buffer_Decouple(chanend c_mix_out
 #ifdef CHAN_BUFF_CTRL
@@ -839,6 +834,7 @@ void XUA_Buffer_Decouple(chanend c_mix_out
                 /* Reset OUT buffer state */
                 SET_SHARED_GLOBAL(g_aud_from_host_rdptr, aud_from_host_fifo_start);
                 SET_SHARED_GLOBAL(g_aud_from_host_wrptr, aud_from_host_fifo_start);
+                SET_SHARED_GLOBAL(aud_data_remaining_to_device, 0);
 
                 /* NOTE, this is potentially usefull for UAC1 */
                 unpackState = 0;

lib_xua/src/core/buffer/ep/ep_buffer.xc

@@ -279,7 +279,6 @@ void XUA_Buffer_Ep(register chanend c_aud_out,
 #if (NUM_USB_CHAN_IN > 0)
     unsigned bufferIn = 1;
 #endif
-    //unsigned remnant = 0;
     unsigned sofCount = 0;
     unsigned freqChange = 0;
 
@@ -469,8 +468,7 @@ void XUA_Buffer_Ep(register chanend c_aud_out,
                         SET_SHARED_GLOBAL(g_freqChange_sampFreq, receivedSampleFreq);
                     }
 #if (AUDIO_CLASS == 2)
-                    else
+                    else if(cmd == SET_STREAM_FORMAT_IN)
-                        if(cmd == SET_STREAM_FORMAT_IN)
                     {
                         unsigned formatChange_DataFormat = inuint(c_aud_ctl);
                         unsigned formatChange_NumChans = inuint(c_aud_ctl);