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Rework the way we scan text for scaler definitions; something weird was going on with sscanf's handling of %n that wasn't obvious. This seems to work around the issue.

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This commit is contained in:
px4dev
2012-12-30 15:09:21 -08:00
parent f2d4eb2887
commit dbb841b0dc
1 changed files with 27 additions and 25 deletions
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apps/systemlib/mixer/mixer_simple.cpp
+27 -25
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@@ -72,17 +72,25 @@ SimpleMixer::~SimpleMixer()
}
static const char *
skipspace(const char *p, unsigned &len)
findtag(const char *buf, unsigned &buflen, char tag)
{
while (isspace(*p)) {
if (len == 0)
return nullptr;
len--;
p++;
while (buflen >= 2) {
if ((buf[0] == tag) && (buf[1] == ':'))
return buf;
buf++;
buflen--;
}
return nullptr;
}
return p;
static void
skipline(const char *buf, unsigned &buflen)
{
const char *p;
/* if we can find a CR or NL in the buffer, skip up to it */
if ((p = (const char *)memchr(buf, '\r', buflen)) || (p = (const char *)memchr(buf, '\n', buflen)))
buflen -= (p - buf);
}
int
@@ -90,20 +98,17 @@ SimpleMixer::parse_output_scaler(const char *buf, unsigned &buflen, mixer_scaler
{
int ret;
int s[5];
int used;
buf = skipspace(buf, buflen);
if (buflen < 16)
buf = findtag(buf, buflen, 'O');
if ((buf == nullptr) || (buflen < 12))
return -1;
if ((ret = sscanf(buf, "O: %d %d %d %d %d%n",
&s[0], &s[1], &s[2], &s[3], &s[4], &used)) != 5) {
if ((ret = sscanf(buf, "O: %d %d %d %d %d",
&s[0], &s[1], &s[2], &s[3], &s[4])) != 5) {
debug("scaler parse failed on '%s' (got %d)", buf, ret);
return -1;
}
buflen -= used;
skipline(buf, buflen);
scaler.negative_scale = s[0] / 10000.0f;
scaler.positive_scale = s[1] / 10000.0f;
@@ -119,20 +124,17 @@ SimpleMixer::parse_control_scaler(const char *buf, unsigned &buflen, mixer_scale
{
unsigned u[2];
int s[5];
int used;
buf = skipspace(buf, buflen);
if (buflen < 16)
buf = findtag(buf, buflen, 'S');
if ((buf == nullptr) || (buflen < 16))
return -1;
if (sscanf(buf, "S: %u %u %d %d %d %d %d%n",
&u[0], &u[1], &s[0], &s[1], &s[2], &s[3], &s[4], &used) != 7) {
if (sscanf(buf, "S: %u %u %d %d %d %d %d",
&u[0], &u[1], &s[0], &s[1], &s[2], &s[3], &s[4]) != 7) {
debug("control parse failed on '%s'", buf);
return -1;
}
buflen -= used;
skipline(buf, buflen);
control_group = u[0];
control_index = u[1];