1 files changed, 61 insertions, 0 deletions

diff --git a/apps/eq_cf.S b/apps/eq_cf.S
new file mode 100644
index 0000000000..3876ca72d6
--- /dev/null
+++ b/apps/eq_cf.S
@@ -0,0 +1,61 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2006 Thom Johansen
+ *
+ * All files in this archive are subject to the GNU General Public License.
+ * See the file COPYING in the source tree root for full license agreement.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+
+    .text
+    .global eq_filter
+eq_filter:
+    lea.l (-11*4, %sp), %sp 
+    movem.l %d2-%d7/%a2-%a6, (%sp)    | save clobbered regs
+    move.l (11*4+8, %sp), %a5         | fetch filter structure address
+    movem.l (11*4+16, %sp), %d6-%d7   | load num. channels and shift count
+    movem.l (%a5), %a0-%a4            | load coefs
+    lea.l (5*4, %a5), %a5             | point to filter history
+    moveq.l #2, %d6                   | number of channels (hardcode to stereo)
+
+.filterloop:
+    move.l (11*4+4, %sp), %a6         | load input channel pointer
+    move.l (%a6), %a6
+    move.l (11*4+12, %sp), %d5        | number of samples
+    addq.l #4, (11*4+4, %sp)          | point x to next channel
+    movem.l (%a5), %d0-%d3            | load filter history
+.loop:
+    move.l (%a6), %d4
+    mac.l %a0, %d4, %acc0               | acc = b0*x[i]
+    mac.l %a1, %d0, %acc0               | acc += b1*x[i - 1]
+    mac.l %a2, %d1, %acc0               | acc += b2*x[i - 2]
+    msac.l %a3, %d2, %acc0              | acc -= a1*y[i - 1]
+    msac.l %a4, %d3, %acc0              | acc -= a2*y[i - 2]
+    move.l %d0, %d1                     | fix history
+    move.l %d4, %d0
+    move.l %d2, %d3
+    movclr.l %acc0, %d2                 | fetch and write result
+    asl.l %d7, %d2                      | restore fixed point format
+    move.l %d2, (%a6)+                  | save result
+    subq.l #1, %d5                      | are we done with this channel?
+    jne .loop
+    
+    movem.l %d0-%d3, (%a5)              | save history back to struct
+    lea.l (4*4, %a5), %a5               | point to next channel's history
+    subq.l #1, %d6                      | have we processed both channels?
+    jne .filterloop
+
+    movem.l (%sp), %d2-%d7/%a2-%a6
+    lea.l (11*4, %sp), %sp
+    rts
+