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drivers/analog: Fix some data alignment issues in the ADC driver.

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This commit is contained in:
Gregory Nutt 2017-07-27 08:09:21 -06:00
parent 552ed255f6
commit e75e3eb807
1 changed files with 40 additions and 10 deletions
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50
drivers/analog/adc.c
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@ -1,7 +1,7 @@
/**************************************************************************** /****************************************************************************
* drivers/analog/adc.c * drivers/analog/adc.c
* *
* Copyright (C) 2008-2009, 2016 Gregory Nutt. All rights reserved. * Copyright (C) 2008-2009, 2016-2017 Gregory Nutt. All rights reserved.
* Copyright (C) 2011 Li Zhuoyi. All rights reserved. * Copyright (C) 2011 Li Zhuoyi. All rights reserved.
* Author: Li Zhuoyi <lzyy.cn@gmail.com> * Author: Li Zhuoyi <lzyy.cn@gmail.com>
* Gregory Nutt <gnutt@nuttx.org> * Gregory Nutt <gnutt@nuttx.org>
@ -237,6 +237,14 @@ static ssize_t adc_read(FAR struct file *filep, FAR char *buffer, size_t buflen)
ainfo("buflen: %d\n", (int)buflen); ainfo("buflen: %d\n", (int)buflen);
/* Determine size of the messages to return.
*
* REVISIT: What if buflen is 8 does that mean 4 messages of size 2? Or
* 2 messages of size 4? What if buflen is 12. Does that mean 3 at size
* 4? Or 4 at size 3? The form of the return data should probably really
* be specified via IOCTL.
*/
if (buflen % 5 == 0) if (buflen % 5 == 0)
{ {
msglen = 5; msglen = 5;
@ -244,6 +252,7 @@ static ssize_t adc_read(FAR struct file *filep, FAR char *buffer, size_t buflen)
else if (buflen % 4 == 0) else if (buflen % 4 == 0)
{ {
msglen = 4; msglen = 4;
}
else if (buflen % 3 == 0) else if (buflen % 3 == 0)
{ {
msglen = 3; msglen = 3;
@ -259,6 +268,7 @@ static ssize_t adc_read(FAR struct file *filep, FAR char *buffer, size_t buflen)
else else
{ {
msglen = 5; msglen = 5;
}
if (buflen >= msglen) if (buflen >= msglen)
{ {
@ -315,36 +325,56 @@ static ssize_t adc_read(FAR struct file *filep, FAR char *buffer, size_t buflen)
if (msglen == 1) if (msglen == 1)
{ {
/* Only one channel,read highest 8-bits */ /* Only one channel, return MS 8-bits of the sample*/
buffer[nread] = msg->am_data >> 24; buffer[nread] = msg->am_data >> 24;
} }
else if (msglen == 2) else if (msglen == 2)
{ {
/* Only one channel, read highest 16-bits */ /* Only one channel, return only the MS 16-bits of the sample.*/
*(int16_t *)&buffer[nread] = msg->am_data >> 16; int16_t data16 = msg->am_data >> 16;
memcpy(&buffer[nread], &data16, 2);
} }
else if (msglen == 3) else if (msglen == 3)
{ {
/* Read channel highest 16-bits */ int16_t data16;
/* Return the channel and the MS 16-bits of the sample. */
buffer[nread] = msg->am_channel; buffer[nread] = msg->am_channel;
*(int16_t *)&buffer[nread + 1] = msg->am_data >> 16; data16 = msg->am_data >> 16;
memcpy(&buffer[nread + 1], &data16, 2);
} }
else if (msglen == 4) else if (msglen == 4)
{ {
/* read channel highest 24-bits */ int32_t data24;
#ifdef CONFIG_ENDIAN_BIG
/* In the big endian case, we simply copy the MS three bytes
* which are indices: 0-2.
*/
data24 = msg->am_data;
#else
/* In the little endian case, indices 0-2 correspond to the
* the three LS bytes.
*/
data24 = msg->am_data >> 8;
#endif
/* Return the channel and the most significant 24-bits */
*(int32_t *)&buffer[nread] = msg->am_data;
buffer[nread] = msg->am_channel; buffer[nread] = msg->am_channel;
memcpy(&buffer[nread + 1], &data24, 3);
} }
else else
{ {
/* Read all */ /* Return the channel and all four bytes of the sample */
*(int32_t *)&buffer[nread + 1] = msg->am_data;
buffer[nread] = msg->am_channel; buffer[nread] = msg->am_channel;
memcpy(&buffer[nread + 1], &msg->am_data, 4);
} }
nread += msglen; nread += msglen;