Ryan Malloy
3915d1784f
An existing product called PG Orbit (a mobile PostgreSQL client) creates a naming conflict. pg_orrery — a database orrery built from Keplerian parameters and SQL instead of brass gears. Build system: control file, Makefile, Dockerfile, docker init script. C source: GUC prefix, PG_FUNCTION_INFO_V1 symbol, header guards, ereport prefixes, comments across ~30 files including vendored SGP4. SQL: all 5 install/migration scripts, function name pg_orrery_ephemeris_info. Tests: 9 SQL suites, 8 expected outputs, standalone DE reader test. Documentation: CLAUDE.md, README.md, DESIGN.md, Starlight site infra, 36 MDX pages, OG renderer, logo SVG, docker-compose, agent threads. All 13 regression suites pass. Docs site builds (37 pages).
141 lines
4.4 KiB
C
141 lines
4.4 KiB
C
/*
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* de_reader.h -- Clean-room JPL Development Ephemeris reader
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*
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* Reads JPL DE430/DE440/DE441 binary ephemeris files.
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* Implements Chebyshev polynomial evaluation via Clenshaw recurrence.
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*
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* No GPL dependency: written from the public JPL binary format spec.
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* No global state: each handle is independently opened/managed.
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*
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* Reference:
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* JPL IOM 312.N-03-009 "The JPL Planetary and Lunar Ephemerides,
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* DE405/LE405" (Standish 1998) — format description.
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*/
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#ifndef PG_ORRERY_DE_READER_H
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#define PG_ORRERY_DE_READER_H
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#include <stdint.h>
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/*
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* JPL DE body targets.
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*
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* The ephemeris stores 13 "body groups" in a specific order.
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* Each group has its own coefficient layout (offset, ncoeff, nsub).
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*/
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#define DE_MERCURY 0
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#define DE_VENUS 1
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#define DE_EMB 2 /* Earth-Moon Barycenter */
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#define DE_MARS 3
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#define DE_JUPITER 4
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#define DE_SATURN 5
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#define DE_URANUS 6
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#define DE_NEPTUNE 7
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#define DE_PLUTO 8
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#define DE_MOON 9 /* Moon (geocentric) */
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#define DE_SUN 10
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#define DE_NUTATION 11 /* nutations (dpsi, deps) */
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#define DE_LIBRATION 12 /* lunar librations */
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#define DE_NUM_BODIES 13
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/*
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* DE reader error codes.
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*/
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#define DE_OK 0
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#define DE_ERR_OPEN -1 /* cannot open file */
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#define DE_ERR_READ -2 /* read() failed or short read */
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#define DE_ERR_HEADER -3 /* header validation failed */
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#define DE_ERR_RANGE -4 /* JD out of ephemeris range */
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#define DE_ERR_BODY -5 /* invalid body target */
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#define DE_ERR_CANARY -6 /* canary validation failed */
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#define DE_ERR_ENDIAN -7 /* byte order detection failed */
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/*
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* Coefficient layout for one body group.
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* Parsed from the header's IPT array.
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*/
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typedef struct de_body_layout
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{
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int offset; /* word offset within record (1-based) */
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int ncoeff; /* number of Chebyshev coefficients per component */
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int nsub; /* number of sub-intervals per record interval */
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} de_body_layout;
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/*
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* DE reader handle.
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*
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* One per PostgreSQL backend. Owns its file descriptor and
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* a pre-allocated coefficient buffer.
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*/
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typedef struct de_handle
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{
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int fd; /* file descriptor */
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int swap_bytes; /* 1 if byte-swapping needed */
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/* Header metadata */
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double start_jd; /* first valid JD */
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double end_jd; /* last valid JD */
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double interval_days; /* days per record */
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double au_km; /* AU in km (from header) */
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double emrat; /* Earth-Moon mass ratio */
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int ncoeff; /* number of doubles per record */
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int de_version; /* e.g. 441 */
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/* Coefficient layout per body group */
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de_body_layout layout[DE_NUM_BODIES];
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/* Record buffer: re-used across queries */
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double *record_buf; /* ncoeff doubles */
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int cached_recno; /* which record is loaded, -1 = none */
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/* Record geometry */
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int record_bytes; /* ncoeff * sizeof(double) */
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long data_offset; /* byte offset to first data record */
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} de_handle;
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/*
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* Open and validate a JPL DE binary file.
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*
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* Returns a heap-allocated handle on success, NULL on failure.
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* Sets *errcode to one of DE_OK / DE_ERR_*.
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* Caller must eventually call de_reader_close().
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*
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* Does NOT use ereport() — caller translates error codes.
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*/
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de_handle *de_reader_open(const char *path, int *errcode);
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/*
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* Get the position of a body relative to a center.
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*
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* target: DE_MERCURY..DE_SUN (0-10)
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* center: DE_SUN (10) for heliocentric, DE_EMB (2) for geocentric, etc.
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* Use -1 for "raw" (no center subtraction)
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* jd: Julian date (TDB)
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* pos[3]: output position in AU (ICRS equatorial frame)
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*
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* Returns DE_OK on success, DE_ERR_* on failure.
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*
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* For Earth position: returns Earth (derived from EMB and Moon)
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* For Moon position with center=Earth: returns geocentric Moon
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*/
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int de_reader_get_pos(de_handle *h, double jd, int target, int center,
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double pos[3]);
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/*
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* Close the DE reader handle and free all resources.
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* Safe to call with NULL handle.
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*/
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void de_reader_close(de_handle *h);
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/*
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* Look up a named constant from the DE header.
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* Returns the value, or NAN if not found (use isnan() to check).
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*/
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double de_reader_get_const(de_handle *h, const char *name);
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#endif /* PG_ORRERY_DE_READER_H */
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