aboutsummaryrefslogtreecommitdiff
path: root/drivers/staging/echo/echo.c
diff options
context:
space:
mode:
authorDavid Rowe <david@rowetel.com>2009-08-23 10:57:53 +0930
committerGreg Kroah-Hartman <gregkh@suse.de>2009-09-15 12:02:16 -0700
commit196e76e86a3a909125daff3d62f0a38761f79c66 (patch)
treef63d60199d90135583304635ad2f4559d352915f /drivers/staging/echo/echo.c
parenta3c0f0aa4f206297ea84f91ffb61c8687e23e1a4 (diff)
Staging: echo: top bit patch
This patch removes the need for the bit_operations.h include file which can now be deleted. It also contains some minor corrections to comments (typos and alignment of ASCII formulas). I have also removed some #if lines that were not necessary. I have tested the patch using a unit test module that runs in kernel mode and have verified that the patched code gives identical results to the previous version using a 8000 sample input sequence. Let me know if you want this unit test, it runs automatically when the module is insmod-ed and outputs a go/no go result: # insmod oslec.ko # dmesg [17191803.480000] oslec_test installed [17191803.480000] Testing OSLEC with 128 taps (16 ms tail) [17191803.496000] Oslec Unit Test PASSED! pass: 8000 fail: 0 Signed-off-by: David Rowe <david@rowetel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/staging/echo/echo.c')
-rw-r--r--drivers/staging/echo/echo.c27
1 files changed, 17 insertions, 10 deletions
diff --git a/drivers/staging/echo/echo.c b/drivers/staging/echo/echo.c
index d05642eec54..548365cd0a4 100644
--- a/drivers/staging/echo/echo.c
+++ b/drivers/staging/echo/echo.c
@@ -106,7 +106,6 @@
#include <linux/module.h>
#include <linux/slab.h>
-#include "bit_operations.h"
#include "echo.h"
#define MIN_TX_POWER_FOR_ADAPTION 64
@@ -221,6 +220,14 @@ static inline void lms_adapt_bg(struct oslec_state *ec, int clean,
}
#endif
+static __inline__ int top_bit(unsigned int bits)
+{
+ if (bits == 0)
+ return -1;
+ else
+ return (int)fls((int32_t)bits)-1;
+}
+
struct oslec_state *oslec_create(int len, int adaption_mode)
{
struct oslec_state *ec;
@@ -347,7 +354,7 @@ int16_t oslec_update(struct oslec_state *ec, int16_t tx, int16_t rx)
/*
* Filter DC, 3dB point is 160Hz (I think), note 32 bit precision
* required otherwise values do not track down to 0. Zero at DC, Pole
- * at (1-Beta) only real axis. Some chip sets (like Si labs) don't
+ * at (1-Beta) on real axis. Some chip sets (like Si labs) don't
* need this, but something like a $10 X100P card does. Any DC really
* slows down convergence.
*
@@ -361,7 +368,7 @@ int16_t oslec_update(struct oslec_state *ec, int16_t tx, int16_t rx)
if (ec->adaption_mode & ECHO_CAN_USE_RX_HPF) {
tmp = rx << 15;
-#if 1
+
/*
* Make sure the gain of the HPF is 1.0. This can still
* saturate a little under impulse conditions, and it might
@@ -371,7 +378,7 @@ int16_t oslec_update(struct oslec_state *ec, int16_t tx, int16_t rx)
* the downstream processing.
*/
tmp -= (tmp >> 4);
-#endif
+
ec->rx_1 += -(ec->rx_1 >> DC_LOG2BETA) + tmp - ec->rx_2;
/*
@@ -453,14 +460,14 @@ int16_t oslec_update(struct oslec_state *ec, int16_t tx, int16_t rx)
therefore the scaled version of (1) is:
(2^30) * f = (2^30) * Beta * clean_bg_rx/P
- factor = (2^30) * Beta * clean_bg_rx/P ----- (2)
+ factor = (2^30) * Beta * clean_bg_rx/P ----- (2)
We have chosen Beta = 0.25 by experiment, so:
- factor = (2^30) * (2^-2) * clean_bg_rx/P
+ factor = (2^30) * (2^-2) * clean_bg_rx/P
- (30 - 2 - log2(P))
- factor = clean_bg_rx 2 ----- (3)
+ (30 - 2 - log2(P))
+ factor = clean_bg_rx 2 ----- (3)
To avoid a divide we approximate log2(P) as top_bit(P),
which returns the position of the highest non-zero bit in
@@ -624,7 +631,7 @@ int16_t oslec_hpf_tx(struct oslec_state *ec, int16_t tx)
if (ec->adaption_mode & ECHO_CAN_USE_TX_HPF) {
tmp = tx << 15;
-#if 1
+
/*
* Make sure the gain of the HPF is 1.0. The first can still
* saturate a little under impulse conditions, and it might
@@ -634,7 +641,7 @@ int16_t oslec_hpf_tx(struct oslec_state *ec, int16_t tx)
* the downstream processing.
*/
tmp -= (tmp >> 4);
-#endif
+
ec->tx_1 += -(ec->tx_1 >> DC_LOG2BETA) + tmp - ec->tx_2;
tmp1 = ec->tx_1 >> 15;
if (tmp1 > 32767)