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hameg-hmo: Replace floating point comparison for vdiv 

This should fix bug #731.
This commit is contained in:
Soeren Apel 2016-01-08 23:02:20 +01:00 committed by Uwe Hermann
parent a5be5d5bc0
commit 8fff75196f
1 changed files with 71 additions and 10 deletions
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81
src/hardware/hameg-hmo/protocol.c
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@ -327,13 +327,75 @@ static int scope_state_get_array_option(struct sr_scpi_dev_inst *scpi,
return SR_OK;
}
/**
* This function takes a value of the form "2.000E-03", converts it to a
* significand / factor pair and returns the index of an array where
* a matching pair was found.
*
* It's a bit convoluted because of floating-point issues. The value "10.00E-09"
* is parsed by g_ascii_strtod() as 0.000000009999999939, for example.
* Therefore it's easier to break the number up into two strings and handle
* them separately.
*
* @param value The string to be parsed.
* @param array The array of s/f pairs.
* @param array_len The number of pairs in the array.
* @param result The index at which a matching pair was found.
*
* @return SR_ERR on any parsing error, SR_OK otherwise.
*/
static int array_float_get(gchar *value, const uint64_t array[][2],
int array_len, int *result)
{
int i;
uint64_t f;
float s;
unsigned int s_int;
gchar ss[10], es[10];
memset(ss, 0, sizeof(ss));
memset(es, 0, sizeof(es));
strncpy(ss, value, 5);
strncpy(es, &(value[6]), 3);
if (sr_atof_ascii(ss, &s) != SR_OK)
return SR_ERR;
if (sr_atoi(es, &i) != SR_OK)
return SR_ERR;
/* Transform e.g. 10^-03 to 1000 as the array stores the inverse. */
f = pow(10, abs(i));
/*
* Adjust the significand/factor pair to make sure
* that f is a multiple of 1000.
*/
while ((int)fmod(log10(f), 3) > 0) {
s *= 10;
f *= 10;
}
/* Truncate s to circumvent rounding errors. */
s_int = (unsigned int)s;
for (i = 0; i < array_len; i++) {
if ((s_int == array[i][0]) && (f == array[i][1])) {
*result = i;
return SR_OK;
}
}
return SR_ERR;
}
static int analog_channel_state_get(struct sr_scpi_dev_inst *scpi,
const struct scope_config *config,
struct scope_state *state)
{
unsigned int i, j;
float tmp_float;
char command[MAX_COMMAND_SIZE];
char *tmp_str;
for (i = 0; i < config->analog_channels; i++) {
g_snprintf(command, sizeof(command),
@ -348,20 +410,19 @@ static int analog_channel_state_get(struct sr_scpi_dev_inst *scpi,
(*config->scpi_dialect)[SCPI_CMD_GET_VERTICAL_DIV],
i + 1);
if (sr_scpi_get_float(scpi, command, &tmp_float) != SR_OK)
if (sr_scpi_get_string(scpi, command, &tmp_str) != SR_OK)
return SR_ERR;
for (j = 0; j < config->num_vdivs; j++) {
if (tmp_float == ((float) (*config->vdivs)[j][0] /
(*config->vdivs)[j][1])) {
state->analog_channels[i].vdiv = j;
break;
}
}
if (j == config->num_vdivs) {
if (array_float_get(tmp_str, hmo_vdivs, ARRAY_SIZE(hmo_vdivs),
&j) != SR_OK) {
g_free(tmp_str);
sr_err("Could not determine array index for vertical div scale.");
return SR_ERR;
}
g_free(tmp_str);
state->analog_channels[i].vdiv = j;
g_snprintf(command, sizeof(command),
(*config->scpi_dialect)[SCPI_CMD_GET_VERTICAL_OFFSET],
i + 1);