From: Keith Packard Date: Wed, 15 Jan 2014 07:21:40 +0000 (-0800) Subject: altos: Switch APRS to compressed position format X-Git-Tag: 1.3.1~19 X-Git-Url: https://git.gag.com/?p=fw%2Faltos;a=commitdiff_plain;h=9d812b3db418fd9816731b761a0853eb38f5a265 altos: Switch APRS to compressed position format This provides lat/lon/alt in fewer bytes while improving precision. Signed-off-by: Keith Packard --- diff --git a/src/drivers/ao_aprs.c b/src/drivers/ao_aprs.c index 6ab61e6a..96e90f00 100644 --- a/src/drivers/ao_aprs.c +++ b/src/drivers/ao_aprs.c @@ -144,6 +144,7 @@ #endif #include +#include // Public methods, constants, and data structures for each class. @@ -254,9 +255,9 @@ typedef enum /// AX.25 compliant packet header that contains destination, station call sign, and path. /// 0x76 for SSID-11, 0x78 for SSID-12 static uint8_t TNC_AX25_HEADER[] = { - 'A' << 1, 'P' << 1, 'A' << 1, 'M' << 1, ' ' << 1, ' ' << 1, 0x60, \ - 'N' << 1, '0' << 1, 'C' << 1, 'A' << 1, 'L' << 1, 'L' << 1, 0x78, \ - 'W' << 1, 'I' << 1, 'D' << 1, 'E' << 1, '2' << 1, ' ' << 1, 0x65, \ + 'A' << 1, 'P' << 1, 'A' << 1, 'M' << 1, ' ' << 1, ' ' << 1, 0x60, + 'N' << 1, '0' << 1, 'C' << 1, 'A' << 1, 'L' << 1, 'L' << 1, 0x78, + 'W' << 1, 'I' << 1, 'D' << 1, 'E' << 1, '2' << 1, ' ' << 1, 0x65, 0x03, 0xf0 }; #define TNC_CALLSIGN_OFF 7 @@ -479,6 +480,14 @@ static void tnc1200TimerTick() } // END switch } +static void tncCompressInt(uint8_t *dest, int32_t value, int len) { + int i; + for (i = len - 1; i >= 0; i--) { + dest[i] = value % 91 + 33; + value /= 91; + } +} + /** * Generate the plain text position packet. */ @@ -487,7 +496,14 @@ static int tncPositionPacket(void) int32_t latitude = ao_gps_data.latitude; int32_t longitude = ao_gps_data.longitude; int32_t altitude = ao_gps_data.altitude; + uint8_t *buf; + if (altitude < 0) + altitude = 0; + altitude = (altitude * (int32_t) 10000 + (3048/2)) / (int32_t) 3048; + +#if 0 + char lat_sign = 'N', lon_sign = 'E'; uint16_t lat_deg; uint16_t lon_deg; uint16_t lat_min; @@ -495,8 +511,6 @@ static int tncPositionPacket(void) uint16_t lon_min; uint16_t lon_frac; - char lat_sign = 'N', lon_sign = 'E'; - if (latitude < 0) { lat_sign = 'S'; latitude = -latitude; @@ -529,15 +543,56 @@ static int tncPositionPacket(void) longitude -= lon_min * 10000000; lon_frac = longitude / 100000; - if (altitude < 0) - altitude = 0; - - altitude = (altitude * (int32_t) 10000 + (3048/2)) / (int32_t) 3048; - +#if 0 return sprintf ((char *) tncBuffer, "=%02u%02u.%02u%c\\%03u%02u.%02u%cO /A=%06u\015", lat_deg, lat_min, lat_frac, lat_sign, lon_deg, lon_min, lon_frac, lon_sign, altitude); +#endif + + return sprintf ((char *) tncBuffer, "/%02u%02u%02uh%02u%02u.%02u%c/%03u%02u.%02u%c'/A=%06u\015", + ao_gps_data.hour, + ao_gps_data.minute, + ao_gps_data.second, + lat_deg, lat_min, lat_frac, lat_sign, + lon_deg, lon_min, lon_frac, lon_sign, + altitude); +#endif + buf = tncBuffer; +#if APRS_TIME + sprintf ((char *) buf, "/%02u%02u%02uh", + ao_gps_data.hour, + ao_gps_data.minute, + ao_gps_data.second); + buf += 8; +#else + *buf++ = '!'; +#endif + + /* Symbol table ID */ + *buf++ = '/'; + + latitude = ((uint64_t) 380926 * (900000000 - latitude)) / 10000000; + longitude = ((uint64_t) 190463 * (1800000000 + longitude)) / 10000000; + +#define ALTITUDE_LOG_BASE 0.001998002662673f /* log(1.002) */ + + altitude = logf((float) altitude) * (1/ALTITUDE_LOG_BASE); + + tncCompressInt(buf, latitude, 4); + buf += 4; + tncCompressInt(buf, longitude, 4); + buf += 4; + + /* Symbol code */ + *buf++ = '\''; + + tncCompressInt(buf, altitude, 2); + buf += 2; + + *buf++ = 33 + ((1 << 5) | (2 << 3)); + *buf++ = '\0'; + return buf - tncBuffer; } static int16_t diff --git a/src/lpc/Makefile-lpc.defs b/src/lpc/Makefile-lpc.defs index dd2bf0e6..fecb9135 100644 --- a/src/lpc/Makefile-lpc.defs +++ b/src/lpc/Makefile-lpc.defs @@ -4,7 +4,7 @@ endif include $(TOPDIR)/Makedefs -vpath % $(TOPDIR)/lpc:$(TOPDIR)/product:$(TOPDIR)/drivers:$(TOPDIR)/core:$(TOPDIR)/util:$(TOPDIR)/kalman:$(TOPDIR/aes):$(TOPDIR) +vpath % $(TOPDIR)/lpc:$(TOPDIR)/product:$(TOPDIR)/drivers:$(TOPDIR)/core:$(TOPDIR)/util:$(TOPDIR)/kalman:$(TOPDIR/aes):$(TOPDIR):$(TOPDIR)/math vpath make-altitude $(TOPDIR)/util vpath make-kalman $(TOPDIR)/util vpath kalman.5c $(TOPDIR)/kalman @@ -28,7 +28,7 @@ CC=$(ARM_CC) WARN_FLAGS=-Wall -Wextra -Werror -AO_CFLAGS=-I. -I$(TOPDIR)/lpc -I$(TOPDIR)/core -I$(TOPDIR)/drivers -I$(TOPDIR)/product -I$(TOPDIR) $(PDCLIB_INCLUDES) +AO_CFLAGS=-I. -I$(TOPDIR)/lpc -I$(TOPDIR)/core -I$(TOPDIR)/drivers -I$(TOPDIR)/product -I$(TOPDIR) -I$(TOPDIR)/math -I$(TOPDIR) $(PDCLIB_INCLUDES) LPC_CFLAGS=-std=gnu99 -mlittle-endian -mcpu=cortex-m0 -mthumb\ -ffreestanding -nostdlib $(AO_CFLAGS) $(WARN_FLAGS) diff --git a/src/math/ef_log.c b/src/math/ef_log.c new file mode 100644 index 00000000..619fe909 --- /dev/null +++ b/src/math/ef_log.c @@ -0,0 +1,92 @@ +/* ef_log.c -- float version of e_log.c. + * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. + */ + +/* + * ==================================================== + * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. + * + * Developed at SunPro, a Sun Microsystems, Inc. business. + * Permission to use, copy, modify, and distribute this + * software is freely granted, provided that this notice + * is preserved. + * ==================================================== + */ + +#include "fdlibm.h" + +#ifdef __STDC__ +static const float +#else +static float +#endif +ln2_hi = 6.9313812256e-01, /* 0x3f317180 */ +ln2_lo = 9.0580006145e-06, /* 0x3717f7d1 */ +two25 = 3.355443200e+07, /* 0x4c000000 */ +Lg1 = 6.6666668653e-01, /* 3F2AAAAB */ +Lg2 = 4.0000000596e-01, /* 3ECCCCCD */ +Lg3 = 2.8571429849e-01, /* 3E924925 */ +Lg4 = 2.2222198546e-01, /* 3E638E29 */ +Lg5 = 1.8183572590e-01, /* 3E3A3325 */ +Lg6 = 1.5313838422e-01, /* 3E1CD04F */ +Lg7 = 1.4798198640e-01; /* 3E178897 */ + +#ifdef __STDC__ +static const float zero = 0.0; +#else +static float zero = 0.0; +#endif + +#ifdef __STDC__ + float __ieee754_logf(float x) +#else + float __ieee754_logf(x) + float x; +#endif +{ + float hfsq,f,s,z,R,w,t1,t2,dk; + __int32_t k,ix,i,j; + + GET_FLOAT_WORD(ix,x); + + k=0; + if (FLT_UWORD_IS_ZERO(ix&0x7fffffff)) + return -two25/zero; /* log(+-0)=-inf */ + if (ix<0) return (x-x)/zero; /* log(-#) = NaN */ + if (!FLT_UWORD_IS_FINITE(ix)) return x+x; + if (FLT_UWORD_IS_SUBNORMAL(ix)) { + k -= 25; x *= two25; /* subnormal number, scale up x */ + GET_FLOAT_WORD(ix,x); + } + k += (ix>>23)-127; + ix &= 0x007fffff; + i = (ix+(0x95f64<<3))&0x800000; + SET_FLOAT_WORD(x,ix|(i^0x3f800000)); /* normalize x or x/2 */ + k += (i>>23); + f = x-(float)1.0; + if((0x007fffff&(15+ix))<16) { /* |f| < 2**-20 */ + if(f==zero) { if(k==0) return zero; else {dk=(float)k; + return dk*ln2_hi+dk*ln2_lo;}} + R = f*f*((float)0.5-(float)0.33333333333333333*f); + if(k==0) return f-R; else {dk=(float)k; + return dk*ln2_hi-((R-dk*ln2_lo)-f);} + } + s = f/((float)2.0+f); + dk = (float)k; + z = s*s; + i = ix-(0x6147a<<3); + w = z*z; + j = (0x6b851<<3)-ix; + t1= w*(Lg2+w*(Lg4+w*Lg6)); + t2= z*(Lg1+w*(Lg3+w*(Lg5+w*Lg7))); + i |= j; + R = t2+t1; + if(i>0) { + hfsq=(float)0.5*f*f; + if(k==0) return f-(hfsq-s*(hfsq+R)); else + return dk*ln2_hi-((hfsq-(s*(hfsq+R)+dk*ln2_lo))-f); + } else { + if(k==0) return f-s*(f-R); else + return dk*ln2_hi-((s*(f-R)-dk*ln2_lo)-f); + } +} diff --git a/src/math/fdlibm.h b/src/math/fdlibm.h index 821619ad..ee9fcb22 100644 --- a/src/math/fdlibm.h +++ b/src/math/fdlibm.h @@ -19,6 +19,7 @@ #define __ieee754_acosf acosf #define __ieee754_sqrtf sqrtf +#define __ieee754_logf logf /* REDHAT LOCAL: Include files. */ #include diff --git a/src/math/math.h b/src/math/math.h index fd543bc2..97dd74cf 100644 --- a/src/math/math.h +++ b/src/math/math.h @@ -34,4 +34,6 @@ float scalbnf(float x, int n); float copysignf(float x, float y); +float logf(float x); + #endif diff --git a/src/telegps-v0.3/Makefile b/src/telegps-v0.3/Makefile index bb9c8c64..5aad32b5 100644 --- a/src/telegps-v0.3/Makefile +++ b/src/telegps-v0.3/Makefile @@ -19,6 +19,9 @@ INC = \ Makefile +MATH_SRC=\ + ef_log.c + ALTOS_SRC = \ ao_interrupt.c \ ao_boot_chain.c \ @@ -47,6 +50,7 @@ ALTOS_SRC = \ ao_log.c \ ao_log_mega.c \ ao_gps_report_mega.c \ + $(MATH_SRC) \ $(SAMPLE_PROFILE) PRODUCT=TeleGPS-v0.3 diff --git a/src/telemega-v0.1/Makefile b/src/telemega-v0.1/Makefile index 0145f49c..35f28b30 100644 --- a/src/telemega-v0.1/Makefile +++ b/src/telemega-v0.1/Makefile @@ -58,7 +58,8 @@ MATH_SRC=\ sf_sin.c \ sf_fabs.c \ sf_floor.c \ - sf_scalbn.c + sf_scalbn.c \ + ef_log.c ALTOS_SRC = \ ao_boot_chain.c \ diff --git a/src/telemega-v1.0/Makefile b/src/telemega-v1.0/Makefile index 543f7e74..b5c1f402 100644 --- a/src/telemega-v1.0/Makefile +++ b/src/telemega-v1.0/Makefile @@ -59,7 +59,8 @@ MATH_SRC=\ sf_fabs.c \ sf_floor.c \ sf_scalbn.c \ - sf_sin.c + sf_sin.c \ + ef_log.c ALTOS_SRC = \ ao_boot_chain.c \ diff --git a/src/telemetrum-v2.0/Makefile b/src/telemetrum-v2.0/Makefile index cebc9cab..0b9e6914 100644 --- a/src/telemetrum-v2.0/Makefile +++ b/src/telemetrum-v2.0/Makefile @@ -37,6 +37,9 @@ INC = \ #STACK_GUARD=ao_mpu_stm.c #STACK_GUARD_DEF=-DHAS_STACK_GUARD=1 +MATH_SRC=\ + ef_log.c + ALTOS_SRC = \ ao_boot_chain.c \ ao_interrupt.c \ @@ -83,6 +86,7 @@ ALTOS_SRC = \ ao_packet.c \ ao_companion.c \ ao_aprs.c \ + $(MATH_SRC) \ $(PROFILE) \ $(SAMPLE_PROFILE) \ $(STACK_GUARD)