diff options
author | Bdale Garbee <bdale@gag.com> | 2012-09-12 20:01:22 -0600 |
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committer | Bdale Garbee <bdale@gag.com> | 2012-09-12 20:01:22 -0600 |
commit | 3b612efcd1dddc6a3d59012f7ed57754b1f798c2 (patch) | |
tree | 18d50713491ef96c5c127a309f870efb6c33f98d /src/core/ao_convert.c | |
parent | e076773c1693e2a62bb828dee71c04c20dbab0a5 (diff) | |
parent | 01eb36408d7e0e826b431fcc1d3b2deb23607e0b (diff) |
Merge branch 'new-debian' into debian
Conflicts:
ChangeLog
debian/altos.install
debian/changelog
debian/control
debian/copyright
debian/dirs
debian/docs
debian/menu
debian/rules
src/Makefile
Diffstat (limited to 'src/core/ao_convert.c')
-rw-r--r-- | src/core/ao_convert.c | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/src/core/ao_convert.c b/src/core/ao_convert.c new file mode 100644 index 00000000..aa9b5f48 --- /dev/null +++ b/src/core/ao_convert.c @@ -0,0 +1,89 @@ +/* + * Copyright © 2009 Keith Packard <keithp@keithp.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; version 2 of the License. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. + */ + +#if !defined(AO_CONVERT_TEST) && !defined(AO_FLIGHT_TEST) +#include "ao.h" +#endif + +static const int16_t altitude_table[] = { +#include "altitude.h" +}; + +#define ALT_FRAC_SCALE (1 << ALT_FRAC_BITS) +#define ALT_FRAC_MASK (ALT_FRAC_SCALE - 1) + +int16_t +ao_pres_to_altitude(int16_t pres) __reentrant +{ + uint8_t o; + int16_t part; + + if (pres < 0) + pres = 0; + o = pres >> ALT_FRAC_BITS; + part = pres & ALT_FRAC_MASK; + + return ((int32_t) altitude_table[o] * (ALT_FRAC_SCALE - part) + + (int32_t) altitude_table[o+1] * part + (ALT_FRAC_SCALE >> 1)) >> ALT_FRAC_BITS; +} + +#if AO_NEED_ALTITUDE_TO_PRES +int16_t +ao_altitude_to_pres(int16_t alt) __reentrant +{ + int16_t span, sub_span; + uint8_t l, h, m; + int32_t pres; + + l = 0; + h = NALT - 1; + while ((h - l) != 1) { + m = (l + h) >> 1; + if (altitude_table[m] < alt) + h = m; + else + l = m; + } + span = altitude_table[l] - altitude_table[h]; + sub_span = altitude_table[l] - alt; + pres = ((((int32_t) l * (span - sub_span) + (int32_t) h * sub_span) << ALT_FRAC_BITS) + (span >> 1)) / span; + if (pres > 32767) + pres = 32767; + if (pres < 0) + pres = 0; + return (int16_t) pres; +} +#endif + +#if 0 +int16_t +ao_temp_to_dC(int16_t temp) __reentrant +{ + int16_t ret; + + /* Output voltage at 0°C = 0.755V + * Coefficient = 0.00247V/°C + * Reference voltage = 1.25V + * + * temp = ((value / 32767) * 1.25 - 0.755) / 0.00247 + * = (value - 19791.268) / 32768 * 1.25 / 0.00247 + * ≃ (value - 19791) * 1012 / 65536 + */ + ret = ((temp - 19791) * 1012L) >> 16; + return ret; +} +#endif |