grib2.h(3)

📦 version 2.3.0, in ubuntu resolute, ubuntu stonking

okay so bestie, you just opened grib2.h(3) from the Library Functions Manual and honestly? iconic. this is the header file page for the NCEPLIBS-g2c library, and it's a big one, so we're doing this in parts. grab a snack 🍓

✨ NAME ✨

grib2.h — the header file for the NCEPLIBS-g2c library. that's the whole vibe. 💅

🌈 SYNOPSIS 🌈

before literally anything else, you pull in these bad boys right here:

#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <sys/types.h>

🦋 Data Structures 🦋

struct gribfield — the struct for a GRIB2 field. the whole field. everything about it. she contains multitudes. 💖

✨ Macros ✨

okay this is the long part, and no, we are not skipping any of them, because every single one matters. buckle up 🫶

G2_ADD_MSG_COMPLETE = -2 — GRIB message already complete. it's done, girl, stop adding to it 💀
G2_ADD_MSG_INIT = -1 — GRIB message was not initialized — you gotta call g2_create() first.
G2_ADDFIELD_BAD_BITMAP = -8 — in g2_addfield() there's no bitmap in the GRIB message.
G2_ADDFIELD_BAD_DRT = -7 — in g2_addfield() there's an unsupported Data Representationi Template. (yes that's the spelling, we don't fix it, we respect it 🎀)
G2_ADDFIELD_BAD_GDS = -6 — in g2_addfield() section 3 (GDS) was not previously defined in the message.
G2_ADDFIELD_BAD_GDT = -9 — in g2_addfield() you need a GDT of one of 5.50 through 5.53 when using DRT 5.51.
G2_ADDFIELD_BAD_PDT = -5 — in g2_addfield() it could not find the requested Product Definition Template.
G2_ADDFIELD_ERR = -10 — in g2_addfield() there was an error packing the data field. 😭
G2_ADDGRID_BAD_GDT = -5 — in g2_addgrid() it could not find the requested Grid Definition Template.
G2_AEC_ENABLED = 1 — decoding/encoding AEC/CCSDS is enabled. slay.
G2_BAD_SEC = -4 — the previous Section was unexpected. rude, honestly.
G2_BAD_SEC_COUNTS = -3 — the sum of Section byte counts doesn't add to the total byte count. math said no 🧚
G2_CREATE_GRIB_VERSION = -1 — wrong GRIB version for g2_create(), it must be 2.
G2_GETFLD_BAD_END = 7 — g2_getfld() didn't find 7777"atendofmessage.
G2_GETFLD_BAD_SEC1 = 15 — error in g2_getfld() unpacking section 1.
G2_GETFLD_BAD_SEC2 = 16 — error in g2_getfld() unpacking section 2.
G2_GETFLD_BAD_SEC3 = 10 — error in g2_getfld() unpacking section 3.
G2_GETFLD_BAD_SEC4 = 11 — error in g2_getfld() unpacking section 4.
G2_GETFLD_BAD_SEC5 = 12 — error in g2_getfld() unpacking section 5.
G2_GETFLD_BAD_SEC6 = 13 — error in g2_getfld() unpacking section 6.
G2_GETFLD_BAD_SEC7 = 14 — error in g2_getfld() unpacking section 7.
G2_GETFLD_GRIB_VERSION = 2 — wrong GRIB version for g2_getfld(), it must be 2.
G2_GETFLD_INVAL = 3 — g2_getfld() data field request number was not positive.
G2_GETFLD_INVAL_SEC = 8 — g2_getfld() encountered an unrecognized section.
G2_GETFLD_NO_BITMAP = 17 — in g2_getfld() a previous bitmap was specified, yet none exists.
G2_GETFLD_NO_DRT = 9 — in g2_getfld(), the Data Representation Template is not implemented.
G2_GETFLD_NO_GRIB = 1 — g2_getfld() can't find the beginning characters GRIB".
G2_GETFLD_WRONG_END = 4 — g2_info() found 7777"notwhereexpected.
G2_GETFLD_WRONG_NFLDS = 6 — in g2_getfld() the message did not contain the requested number of data fields.
G2_GRIBEND_MSG_INIT = -1 — in g2_gribend() the GRIB message was not initialized — you gotta call g2_create() first.
G2_INFO_BAD_END = 5 — g2_info() didn't find 7777"atendofmessage.
G2_INFO_GRIB_VERSION = 2 — wrong GRIB version for g2_info(), it must be 2.
G2_INFO_INVAL_SEC = 6 — g2_info() found an invalid section number.
G2_INFO_NO_GRIB = 1 — g2_info() can't find the beginning characters GRIB".
G2_INFO_NO_SEC1 = 3 — g2_info() can't find section 1.
G2_INFO_WRONG_END = 4 — g2_info() found 7777"notwhereexpected.
G2_JASPER_DECODE = -3 — in dec_jpeg2000() there was an error decoding the image with jasper.
G2_JASPER_DECODE_COLOR = -5 — in dec_jpeg2000() the decoded image had multiple color components.
G2_JASPER_ENCODE = -3 — in enc_jpeg2000() there was an error encoding the image with jasper.
G2_JASPER_INIT = -2 — in enc_jpeg2000()/dec_jpeg2000() there was an error initializing the jasper library.
G2_JPCUNPACK_MEM = 1 — in jpcunpack() or another unpack function: out of memory. 💀
G2_JPEG2000_ENABLED = 1 — decoding/encoding JPEG2000 is enabled. ate.
G2_NO_ERROR = 0 — the function succeeded. we love to see it 👑
G2_PNG_ENABLED = 1 — decoding/encoding PNG is enabled.
G2_SPECUNPACK_TYPE = -3 — in specunpack() it can't handle 64 or 128 bit floats.
G2_UNPACK3_BAD_GDT = 5 — in g2_unpack3(), undefined Grid Definition Template.
G2_UNPACK4_BAD_PDT = 5 — in g2_unpack4(), undefined Product Definition Template.
G2_UNPACK5_BAD_DRT = 7 — in g2_unpack5(), undefined Data Representation Template.
G2_UNPACK6_BAD_BITMAP = 4 — in g2_unpack6(), unrecognized pre-defined bit-map.
G2_UNPACK7_BAD_DRT = 4 — in g2_unpack7(), unrecognized Data Representation Template.
G2_UNPACK7_CORRUPT_SEC = 7 — in g2_unpack7(), corrupt section 7.
G2_UNPACK7_WRONG_GDT = 5 — in g2_unpack7(), you need one of GDT 3.50 through 3.53 to decode DRT 5.51.
G2_UNPACK_BAD_SEC = 2 — bad section number in the unpacking function.
G2_UNPACK_NO_MEM = 6 — error allocating memory in the unpack function.
G2C_AEC_DRS_TEMPLATE_LEN = 8 — length of the idrstmpl array for AEC packing.
G2C_BYTE = 1 — signed 1 byte integer.
G2C_CHAR = 2 — ISO/ASCII character.
G2C_CLOBBER = 0x0000 — destroy the existing file. bestie. that file is GONE 😭
G2C_DOUBLE = 6 — double precision floating point number.
G2C_EAEC = (-74) — error encoding/decoding AEC data.
G2C_EBADEND = (-65) — end of message in the wrong place.
G2C_EBADID = (-55) — bad ID.
G2C_EBADSECTION = (-66) — invalid section number.
G2C_EBADTEMPLATE = (-70) — template problem.
G2C_EBADTYPE = (-73) — type not found.
G2C_ECSV = (-75) — CSV error.
G2C_EFILE = (-54) — file I/O error.
G2C_EINVAL = (-53) — invalid input.
G2C_EJPEG = (-67) — error encoding/decoding JPEG data.
G2C_EMSG = (-58) — error decoding GRIB message.
G2C_EMSGCOMPLETE = (-51) — GRIB message already complete.
G2C_ENAMETOOLONG = (-52) — name too long.
G2C_ENOEND = (-64) — cannot find the end of the GRIB message.
G2C_ENOMEM = (-57) — out of memory.
G2C_ENOMSG = (-59) — no GRIB message found.
G2C_ENOPARAM = (-71) — parameter not found.
G2C_ENOPRODUCT = (-72) — product not found.
G2C_ENOSECTION = (-63) — cannot find section.
G2C_ENOTEMPLATE = (-69) — template not found.
G2C_ENOTFOUND = (-61) — table or entry not found.
G2C_ENOTGRIB = (-50) — GRIB header not found.
G2C_ENOTGRIB2 = (-62) — not GRIB 2.
G2C_EPNG = (-68) — error encoding/decoding PNG data.
G2C_ERROR = 1 — general error code, returned for some test errors.
G2C_ETOOMANYFILES = (-56) — trying to open too many files.
G2C_EXML = (-60) — XML error.
G2C_FLOAT = 5 — single precision floating point number.
G2C_INT = 4 — signed 4 byte integer.
G2C_INT64 = 10 — signed 8-byte int.
G2C_JASPER_MAX_MEM — maximum size for the Jasper memory buffer. (no value attached, she's just vibes ✨)
G2C_JPEG_DRS_TEMPLATE_LEN = 7 — length of the idrstmpl array for JPEG packing.
G2C_LARGE_FILE_INDEX = 0x0008 — create a large file index.
G2C_MAX_DRS_TEMPLATE = 11 — maximum number of DRS templates.
G2C_MAX_DRS_TEMPLATE_MAPLEN = 18 — maximum DRS template map length.
G2C_MAX_FILES = 3 — maximum number of open files.
G2C_MAX_GDS_TEMPLATE = 38 — maximum number of grid templates.
G2C_MAX_GDS_TEMPLATE_MAPLEN = 28 — maximum grid template map length.
G2C_MAX_GRIB_CODE_LEN = 20 — maximum length of code.
G2C_MAX_GRIB_DESC_LEN = 512 — maximum length of code description.
G2C_MAX_GRIB_LEVEL_DESC_LEN = 40 — maximum length of level description.
G2C_MAX_GRIB_STATUS_LEN = 40 — maximum length of code status.
G2C_MAX_GRIB_TITLE_LEN = 200 — maximum length of code table title.
G2C_MAX_NAME = 1024 — maximum length of a name.
G2C_MAX_NOAA_ABBREV_LEN = 11 — maximum length of a NOAA abbreviation of a parameter.
G2C_MAX_NOAA_PARAM_LINE_LEN = 120 — maximum length of a line in the NOAA abbreviation CSV file.
G2C_MAX_NOAA_PARAMS = 2000 — maximum number of known parameters with NOAA abbreviations.
G2C_MAX_NUM_SECTIONS = 1024 — maximum number of sections that can be handled in one message.
G2C_MAX_PDS_TEMPLATE = 102 — maximum number of PDS templates.
G2C_MAX_PDS_TEMPLATE_MAPLEN = 50 — maximum template map length.
G2C_NOCLOBBER = 0x0004 — don't destroy the existing file. (the respectful option 🫶)
G2C_NOERROR = 0 — no error.
G2C_NOWRITE = 0x0000 — set read-only access for g2c_open().
G2C_PNG_DRS_TEMPLATE_LEN = 5 — length of the idrstmpl array for PNG packing.
G2C_PNG_HEIGHT_MAX = 100000 — maximum height of a PNG grid.
G2C_PNG_WIDTH_MAX = 100000000 — maximum width of a PNG grid.
G2C_SECTION0_ARRAY_LEN = 3 — length of the section 0 array.
G2C_SECTION0_BYTES = 16 — number of bytes in section 0.
G2C_SECTION0_LEN = 3 — length of the section 0 array.
G2C_SECTION1_ARRAY_LEN = 13 — length of the section 1 array.
G2C_SECTION1_BYTES = 21 — number of bytes in section 1 (not including reserved, optional data at the end of the section).
G2C_SECTION1_LEN = 13 — length of the section 1 array.
G2C_SHORT = 3 — signed 2 byte integer.
G2C_UBYTE = 7 — unsigned 1 byte int.
G2C_UINT = 9 — unsigned 4-byte int.
G2C_UINT64 = 11 — unsigned 8-byte int.
G2C_USHORT = 8 — unsigned 2-byte int.
G2C_VERSION = '2.3.0' — current version of the NCEPLIBS-g2c library. 💜
G2C_WRITE = 0x0001 — set read-write access for g2c_open().

🎀 Typedefs 🎀

typedef float g2float — float type.
typedef int64_t g2int — long integer type.
typedef uint64_t g2intu — unsigned long integer type.
typedef struct gribfield gribfield — the struct for a GRIB field. her again, still iconic 💖

part 1 done, bestie — there's more coming, don't go anywhere 🦋

🦋 Functions 🦋

okay bestie, this is the entire function roster — every signature, every one-liner, zero skips, no crumbs left behind 🍓 grab a snack, we're doing all of them.

g2int g2_addfield (unsigned char *cgrib, g2int ipdsnum, g2int *ipdstmpl, float *coordlist, g2int numcoord, g2int idrsnum, g2int *idrstmpl, float *fld, g2int ngrdpts, g2int ibmap, g2int *bmap) — packs sections 4 through 7 and adds them onto a GRIB2 message. section stacking, but make it cute 🎀
g2int g2_addgrid (unsigned char *cgrib, g2int *igds, g2int *igdstmpl, g2int *ideflist, g2int idefnum) — packs a Grid Definition Section (Section 3) and adds it onto a GRIB2 message. grid goes in, grid goes on 📐
g2int g2_addlocal (unsigned char *cgrib, unsigned char *csec2, g2int lcsec2) — adds a Local Use Section (Section 2) onto a GRIB2 message. your lil local secret, tucked in 🙈
g2int g2_create (unsigned char *cgrib, g2int *listsec0, g2int *listsec1) — initializes a brand new GRIB2 message and packs GRIB2 Section 0 (Indicator Section) and Section 1 (Identification Section). birth of a message, main character energy ✨
void g2_free (gribfield *gfld) — frees the memory that was allocated for struct gribfield. cleanup era 🧹
g2int g2_getfld (unsigned char *cgrib, g2int ifldnum, g2int unpack, g2int expand, gribfield **gfld) — hands you back all the metadata, the template values, the bit-map (if there is one), and the unpacked data for a data field. the full reveal 💖
g2int g2_gribend (unsigned char *cgrib) — finalizes a GRIB2 message once all the grids and fields have been added. closing the chapter, periodt 🔥
g2int g2_info (unsigned char *cgrib, g2int *listsec0, g2int *listsec1, g2int *numfields, g2int *numlocal) — searches through a GRIB2 message and returns how many gridded fields it found in there, plus the number (and the maximum size) of Local Use Sections. receipts, but for message structure 🧾
g2int g2_unpack1 (unsigned char *cgrib, g2int *iofst, g2int **ids, g2int *idslen) — unpacks Section 1 — the Identification Section — of a GRIB2 message. 🪪
g2int g2_unpack2 (unsigned char *cgrib, g2int *iofst, g2int *lencsec2, unsigned char **csec2) — unpacks Section 2 (the Local Use Section) of a GRIB2 message. 🎁
g2int g2_unpack3 (unsigned char *cgrib, g2int *iofst, g2int **igds, g2int **igdstmpl, g2int *mapgridlen, g2int **ideflist, g2int *idefnum) — unpacks Section 3 (the Grid Definition Section) of a GRIB2 message. 🗺️
g2int g2_unpack4 (unsigned char *cgrib, g2int *iofst, g2int *ipdsnum, g2int **ipdstmpl, g2int *mappdslen, float **coordlist, g2int *numcoord) — unpacks Section 4 (the Product Definition Section) of a GRIB2 message. 📦
g2int g2_unpack5 (unsigned char *cgrib, g2int *iofst, g2int *ndpts, g2int *idrsnum, g2int **idrstmpl, g2int *mapdrslen) — unpacks Section 5 (the Data Representation Section) of a GRIB2 message. 🧬
g2int g2_unpack6 (unsigned char *cgrib, g2int *iofst, g2int ngpts, g2int *ibmap, g2int **bmap) — unpacks Section 6 (the Bit-Map Section) of a GRIB2 message. little dots, big meaning ⚫
g2int g2_unpack7 (unsigned char *cgrib, g2int *iofst, g2int igdsnum, g2int *igdstmpl, g2int idrsnum, g2int *idrstmpl, g2int ndpts, float **fld) — this subroutine unpacks Section 7 (the Data Section) of a GRIB2 message. the actual numbers, bestie 🌈
int g2c_aecpackd (double *fld, size_t width, size_t height, int *idrstmpl, unsigned char *cpack, size_t *lcpack) — packs up a double array into an AEC code stream. squish it down, doubles 🗜️
int g2c_aecpackf (float *fld, size_t width, size_t height, int *idrstmpl, unsigned char *cpack, size_t *lcpack) — packs up a float array into an AEC code stream. 🗜️
int g2c_aecunpackd (unsigned char *cpack, size_t len, int *idrstmpl, size_t ndpts, double *fld) — unpacks AEC compressed data into an array of doubles, using the info from GRIB2 Data Representation Template 5.42. 🪄
int g2c_aecunpackf (unsigned char *cpack, size_t len, int *idrstmpl, size_t ndpts, float *fld) — unpacks AEC compressed data into an array of floats, using the info from GRIB2 Data Representation Template 5.42. 🪄
int g2c_close (int g2cid) — closes a GRIB2 file and frees the resources. bye babe, take your memory with you 👋
int g2c_compare (int g2cid1, int g2cid2) — compares the metadata of two open GRIB2 files. vibe check, but for metadata ⚖️
int g2c_csv_init () — initializes tables from CodeFlag.txt". 📊
int g2c_dec_aec (unsigned char *cpack, int len, int nbits, int flags, int block_size, int rsi, unsigned char *cfld, int cfldlen) — decodes an AEC code stream specified in the CCSDS 121.0-B-3 Blue Book. 📘
int g2c_dec_jpeg2000 (char *injpc, size_t bufsize, int *outfld) — decodes a JPEG2000 code stream specified in the JPEG2000 Part-1 standard (i.e., ISO/IEC 15444-1) using JasPer Software. 🖼️
int g2c_dec_png (unsigned char *pngbuf, int *width, int *height, unsigned char *cout) — decodes PNG. 🌷
int g2c_degrib2 (int g2cid, const char *fileout) — writes a summary file like the degrib2 utility does. 📝
int g2c_enc_aec (unsigned char *data, int ctemplen, int nbits, int flags, int block_size, int rsi, unsigned char *aecbuf, int *aecbuflen) — encodes data into an AEC code stream specified in the CCSDS 121.0-B-3 Blue Book. 📘
int g2c_enc_jpeg2000 (unsigned char *cin, int width, int height, int nbits, int ltype, int ratio, int retry, char *outjpc, size_t jpclen) — encodes a grayscale image into a JPEG2000 code stream specified in the JPEG2000 Part-1 standard (i.e., ISO/IEC 15444-1) using JasPer Software. 🖼️
int g2c_enc_png (unsigned char *data, int width, int height, int nbits, unsigned char *pngbuf) — encodes PNG. 🌷
int g2c_find_desc (char *title, int code, char *desc) — given a table title and an integer code, finds you a description. 🔍
int g2c_find_desc_str (char *title, char *code, char *desc) — given a table title and a code, finds you a description. 🔍
int g2c_find_msg2 (int g2cid, size_t skip_bytes, size_t max_bytes, size_t *bytes_to_msg, size_t *bytes_in_msg) — searches a file for the next GRIB1 or GRIB2 message. 🕵️
void g2c_free_tables () — frees the table memory. tables cleared, no crumbs 🧹
void g2c_gbit_int (unsigned char *in, int *iout, int iskip, int nbits) — extracts arbitrary size values out of a packed bit string, right justifying each value in the unpacked iout array. 🧷
int g2c_gbits_int (unsigned char *in, int *iout, int iskip, int nbits, int nskip, int n) — extracts arbitrary size values out of a packed bit string, right justifying each value in the unpacked iout array. same energy, more args 🧷
int g2c_get_drs_template (int drs_template_num, int *maplen, int *map, int *needext) — gets DRS template information. 📋
int g2c_get_gdt_len (int grid_template_num, int *maplen) — gets the initial length (number of entries) in the static part of a Grid Definition Template. 📏
int g2c_get_grid_template (int grid_template_num, int *maplen, int *map, int *needext) — gets grid template information. 📋
int g2c_get_grid_template_extension (int grid_template_num, int *g2c_template, int *extlen, int *ext) — gets grid template extension information. 📋
int g2c_get_msg (int g2cid, size_t skip_bytes, size_t max_bytes, size_t *bytes_to_msg, size_t *bytes_in_msg, unsigned char **cbuf) — searches a file for the next GRIB1 or GRIB2 message, and reads it, allocating space in memory to hold that message. find it AND hold it, multi-tasking queen 💅
int g2c_get_pds_template (int pds_template_num, int *maplen, int *map, int *needext) — gets PDS template information. 📋
int g2c_get_pds_template_extension (int pds_template_num, int *g2c_template, int *extlen, int *ext) — gets pds template extension information. 📋
int g2c_get_pdt_len (int pds_template_num, int *maplen) — gets the initial length (number of entries) in the static part of a PDS template. 📏
int g2c_get_prod (int g2cid, int msg_num, int prod_num, int *num_data_points, float *data) — reads the data for a product. 📖
int g2c_inq (int g2cid, int *num_msg) — learns about a GRIB2 file. getting to know u fr fr 🫶
int g2c_inq_dim (int g2cid, int msg_num, int prod_num, int dim_num, size_t *len, char *name, float *val) — learns about one of the dimensions of a GRIB2 product. 📐
int g2c_inq_dim_info (int g2cid, int msg_num, int prod_num, int dim_num, size_t *len, char *name) — learns about one of the dimensions of a GRIB2 product. 📐
int g2c_inq_msg (int g2cid, int msg_num, unsigned char *discipline, int *num_fields, int *num_local, short *center, short *subcenter, unsigned char *master_version, unsigned char *local_version) — learns about a GRIB2 message. 💌
int g2c_inq_msg_time (int g2cid, int msg_num, unsigned char *sig_ref_time, short *year, unsigned char *month, unsigned char *day, unsigned char *hour, unsigned char *minute, unsigned char *second) — learns about the date/time information in a GRIB2 message. ⏰
int g2c_inq_prod (int g2cid, int msg_num, int prod_num, int *pds_template_len, long long int *pds_template, int *gds_template_len, long long int *gds_template, int *drs_template_len, long long int *drs_template) — inquires about a product. all the deets, all three templates 🧐
int g2c_jpcpackd (double *fld, size_t width, size_t height, int *idrstmpl, unsigned char *cpack, size_t *lcpack) — packs up a double array into a JPEG2000 code stream. 🗜️
int g2c_jpcpackf (float *fld, size_t width, size_t height, int *idrstmpl, unsigned char *cpack, size_t *lcpack) — packs up a float array into a JPEG2000 code stream. 🗜️
int g2c_jpcunpackd (unsigned char *cpack, size_t len, int *idrstmpl, size_t ndpts, double *fld) — unpacks JPEG2000 compressed data into an array of doubles, using the info from GRIB2 Data Representation Template 5.40 or 5.40000. 🪄
int g2c_jpcunpackf (unsigned char *cpack, size_t len, int *idrstmpl, size_t ndpts, float *fld) — unpacks JPEG2000 compressed data into an array of floats, using the info from GRIB2 Data Representation Template 5.40 or 5.40000. 🪄
int g2c_log_file (int g2cid) — prints a summary of the contents of an open GRIB2 file. 🪵
int g2c_open (const char *path, int mode, int *g2cid) — opens an existing GRIB2 file. come on in bestie 🚪
int g2c_open_index (const char *data_file, const char *index_file, int mode, int *g2cid) — opens a GRIB2 file with the help of an index file. 🗂️
int g2c_open_index1 (const char *index_file) — opens a GRIB1 index file and reads the contents. 🗂️
int g2c_param_abbrev (int g2disc, int g2cat, int g2num, char *abbrev) — gets the NOAA abbreviation for a GRIB2 parameter. 🏷️
int g2c_param_all (int param_idx, int *g1ver, int *g1val, int *g2disc, int *g2cat, int *g2num, char *abbdrev) — returns all the information about a parameter. the whole lore drop 📚
int g2c_param_g1tog2 (int g1val, int g1ver, int *g2disc, int *g2cat, int *g2num) — translates a GRIB1 parameter to a GRIB2 parameter. 🔄
int g2c_param_g2tog1 (int g2disc, int g2cat, int g2num, int *g1val, int *g1ver) — translates a GRIB2 parameter to a GRIB1 parameter. 🔄
int g2c_pngpackd (double *fld, size_t width, size_t height, int *idrstmpl, unsigned char *cpack, int *lcpack) — this subroutine packs up a double data field into PNG image format. 🎨
int g2c_pngpackf (float *fld, size_t width, size_t height, int *idrstmpl, unsigned char *cpack, int *lcpack) — …

Okay bestie, we're still in the function lineup, so let's keep it moving 💅

This subroutine packs up a float data field into PNG image format.

int g2c_pngunpackd (unsigned char *cpack, size_t len, int *idrstmpl,
    size_t ndpts, double *fld)

This one unpacks a data field that got packed into PNG image format, using the info from the GRIB2 Data Representation Template 5.41 or 5.40010.

int g2c_pngunpackf (unsigned char *cpack, size_t len, int *idrstmpl,
    size_t ndpts, float *fld)

Same energy, also unpacks a data field packed into PNG image format using info from GRIB2 Data Representation Template 5.41 or 5.40010.

int g2c_seekmsg (int g2cid, size_t skip, size_t *offset, size_t *msglen)

Search a file for the next GRIB2 Message. it's giving "where's the message, bestie" 🔍

int g2c_set_log_level (int new_level)

Use this to set the global log level. yes she has a volume knob, and yes you can turn her up 🔊

const char * g2c_strerror (int g2cerr)

Hand it an error code, she hands you back an error message. emotional support for your errno 💖

int g2c_unpack7 (unsigned char *cgrib, int igdsnum, int gds_tmpl_len,
    long long int *gdstmpl, int idrsnum, int drs_tmpl_len, long long int
    *drstmpl, int ndpts, float *fld)

This subroutine unpacks Section 7 (Data Section) of a GRIB2 message. the main character section fr fr ✨

int g2c_write_index (int g2cid, int mode, const char *index_file)

Create an index file from a GRIB2 file, just like the ones the grb2index utility makes. matching sets, iconic 👑

void seekgb (FILE *lugb, g2int iseek, g2int mseek, g2int *lskip, g2int
    *lgrib)

Search a file for the next GRIB Message.

💫 Detailed Description 💫

Header file for NCEPLIBS-g2c library. that's the whole vibe, she's the blueprint 🎀

📜 Program History Log 📜

2002-10-25 — Gilbert — Initial
2009-01-14 — Vuong — Changed struct template to gtemplate
2021-11-9 — Ed Hartnett — Moved many prototypes to new internal header grib2_int.h.
2022-04-15 — Ed Hartnett — Added error codes related to JPEG.
2022-08-15 — Ed Hartnett — Added compression functions for double.
2023-09-10 — Eric Engle — Added AEC compression.

✍️ Author

Stephen Gilbert

📅 Date

2002-10-25

✍️ Author

Ed Hartnett

📂 Definition in file

grib2.h.

🧬 Data Type Documentation 🧬

🌸 struct gribfield 🌸

Struct for GRIB2 field. the moment, the icon, the legend 💖

Definition at line 45 of file grib2.h.

Data Fields:

g2int * bmap — Integer array holding the decoded bitmap, if ibmap=0 or ibap=254. Otherwise NULL.
float * coord_list — Array holding floating point values meant to document the vertical discretisation associated to model data on hybrid coordinate vertical levels (part of Section 4).
g2int discipline — Message Discipline (see Table 0.0).
g2int expanded — Logical value saying whether the data field was expanded to the grid in the case where a bit-map is present. If true, the data points in fld match the grid points and zeros were inserted at grid points where data was bit-mapped out. If false, the data values in ld were not expanded to the grid and are just a consecutive array of data points corresponding to each value of "1" in bmap.
float * fld — Array of ndpts unpacked data points.
g2int griddef — Source of grid definition (see Table 3.0).
- 0 Specified in Table 3.1.
- 1 Predetermined grid Defined by originating centre.
g2int ibmap — Bitmap indicator (see Table 6.0).
- 0 bitmap applies and is included in Section 6.
- 1-253 = Predefined bitmap applies
- 254 = Previously defined bitmap applies to this field
- 255 = Bit map does not apply to this product.
g2int idrtlen — Number of elements in idrtmpl.
g2int * idrtmpl — Contains the data values for the Data Representation Template specified by idrtnum.
g2int idrtnum — Data Representation Template Number (see Table 5.0).
g2int * idsect — Contains the entries in the Identification Section (Section 1).
- idsect[0] Identification of originating Centre (see Table 0). 7 is the identification for the US National Weather Service.
- idsect[1] Identification of originating Sub-centre. (See Table C).
- idsect[2] GRIB Master Tables Version Number (see Table 1.0).
  - 0 Experimental
  - 1 Initial operational version number
- idsect[3] GRIB Local Tables Version Number (see Table 1.1).
  - 0 Local tables not used
  - 1-254 Number of local tables version used
- idsect[4] Significance of Reference Time (See Table 1.2).
  - 0 Analysis
  - 1 Start of forecast
  - 2 Verifying time of forecast
  - 3 Observation time
- idsect[5] Year (4 digits)
- idsect[6] Month
- idsect[7) Day
- idsect[8] Hour
- idsect[9] Minute
- idsect[10] Second
- idsect[11] Production status of processed data (see Table 1.3).
  - 0 Operational products
  - 1 Operational test products
  - 2 Research products
  - 3 Re-analysis products
- idsect[12] Type of processed data (see Table 1.4).
  - 0 Analysis products
  - 1 Forecast products
  - 2 Analysis and forecast products
  - 3 Control forecast products
  - 4 Perturbed forecast products
  - 5 Control and perturbed forecast products
  - 6 Processed satellite observations
  - 7 Processed radar observations
g2int idsectlen — Number of elements in idsect.
g2int ifldnum — Field number within GRIB message.
g2int igdtlen — Number of elements in igdtmpl - i.e. number of entries in Grid Defintion Template.
g2int * igdtmpl — Contains the data values for the Grid Definition Template specified by igdtnum.
g2int igdtnum — Grid Definition Template Number (See Table 3.1).
g2int interp_opt — Interpretation of list for optional points definition. (See Table 3.11).
g2int ipdtlen — Number of elements in ipdtmpl - i.e. number of entries in Product Defintion Template.
g2int * ipdtmpl — Contains the data values for the Product Definition Template specified by ipdtnum.
g2int ipdtnum — Product Definition Template Number (see Table 4.0).
g2int * list_opt — (Used if numoct_opt .ne. 0) This array contains the number of grid points contained in each row (or column) (part of Section 3). NULL if numoct_opt = 0.
unsigned char * local — Pointer to character array containing contents of Local Section 2, if included.
g2int locallen — Length of array local.
g2int ndpts — Number of data points unpacked and returned.
g2int ngrdpts — Number of grid points in the defined grid.
g2int num_coord — Number of values in array coord_list.
g2int num_opt — (Used if numoct_opt .ne. 0) The number of entries in array ideflist - i.e. number of rows (or columns) for which optional grid points are defined. This value is set to zero, if numoct_opt=0.
g2int numoct_opt — Number of octets needed for each additional grid points definition. Used to define number of points in each row (or column) for non-regular grids. = 0, if using regular grid.
g2int unpacked — Logical value saying whether the bitmap and data values were unpacked. If false, bmap and fld pointers are NULL.
g2int version — GRIB edition number (2).

🎀 Macro Definition Documentation 🎀

🔥 `G2_ADD_MSG_COMPLETE` 🔥

#define G2_ADD_MSG_COMPLETE   -2

GRIB message already complete. Cannot add new section. sorry babe, the message said goodbye 💀

Definition at line 473 of file grib2.h.

Referenced by g2_addfield(), g2_addgrid(), g2_addlocal(), and g2_gribend().

🔥 `G2_ADD_MSG_INIT` 🔥

#define G2_ADD_MSG_INIT   -1

GRIB message was not initialized - call g2_create() first. you forgot to start it bestie, go start it 😭

Definition at line 472 of file grib2.h.

Referenced by g2_addfield(), g2_addgrid(), g2_addlocal(), and g2_gribend().