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view intercom/gsm/rpeltp.c @ 5:f762bf195c4b
import spandsp-0.0.3
| author | Peter Meerwald <pmeerw@cosy.sbg.ac.at> |
|---|---|
| date | Fri, 25 Jun 2010 16:00:21 +0200 |
| parents | 13be24d74cd2 |
| children |
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/* v1.0 - 12/Apr/1994 ============================================================================= U U GGG SSSS TTTTT U U G S T U U G GG SSSS T U U G G S T UUU GG SSS T ======================================== ITU-T - USER'S GROUP ON SOFTWARE TOOLS ======================================== MODULE: RPELTP.C - GSM 06.10 RPE-LTP SPEECH ENCODING ALGORITHM ORIGINAL BY: The driving routines of this module were written by: Simao Ferraz de Campos Neto DDS/Pr11 Tel: +55-192-39-6637 CPqD/Telebras Fax: +55-192-39-6125 13088-061 Campinas SP Brazil E-mail: <simao@cpqd.ansp.br> The true implementation was done by Jutta Deneger (jutta@cs.tu-berlin.de) Carsten Borman (cabo@cs.tu-berlin.de) Communications and Operating Systems Research Group (KBS) Technishe Universitaet Berlin The portability changes on the code and rearrangement were done by <simao> DATE: 12/Apr/1994: 18H00 -3H00GMT RELEASE: 1.00 PROTOTYPES: see rpeltp.h for driving-routine prototypes, gsm.h for general prototypes, and private.h for special definitions. OBSERVATION: Copyright note by the original authors: " Copyright 1992 by Jutta Degener and Carsten Bormann, Technische Universitaet Berlin. See the accompanying file "COPYRIGHT" for details. THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE." FUNCTIONS: (Only UGST user-level functions!) rpeltp_init() ......... Initializes the state variable for the encoding or the decoding algorithm. Each need a separate state variable!!! rpeltp_delete ......... Delete the state variable allocation, etc (an alias). rpeltp_encode ......... Entry-level function for the encoding algorithm. rpeltp_decode ......... Entry-level function for the decoding algorithm. ============================================================================ */ #include <stdio.h> /* For NULL */ #include "private.h" #include "gsm.h" #include "rpeltp.h" /* *** Alias functions *** */ /* ------------------------------------------------------------------------ void rpeltp_delete(gsm_state *st); ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Description: ~~~~~~~~~~~~ Frees memory of a state variable previously initialized by a call to rpeltp_init(). This is an alias to the function gsm_destroy() implemented by the original authors of the module. Variables: ~~~~~~~~~~ A pointer to a valid encoder or decoder state variable. Return value: ~~~~~~~~~~~~~ None. Prototype: in gsm.h ~~~~~~~~~~ Original author: ~~~~~~~~~~~~~~~~ Simao Ferraz de Campos Neto DDS/Pr11 Tel: +55-192-39-6637 CPqD/Telebras Fax: +55-192-39-6125 13088-061 Campinas SP Brazil E-mail: <simao@cpqd.ansp.br> Log of changes: ~~~~~~~~~~~~~~~ 12.Apr.94 v.1.0 created. ------------------------------------------------------------------------ */ /* #define rpeltp_delete gsm_destroy / * This is already done in rpeltp.h !!! */ /* ................... End of rpeltp_delete() ......................... */ /* *** True functions *** */ /* ------------------------------------------------------------------------ gsm_state *rpeltp_init(void); ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Description: ~~~~~~~~~~~~ Allocates memory for the state variable of the encoder or the decoder, and resets flags to proper initial values. This includes processing strictly according to the Rec. GSM 06.10. In a encoder plus decoder calling program there must exist different state variables for the encoder and for the decoder. Variables: ~~~~~~~~~~ None. Return value: ~~~~~~~~~~~~~ Returns a pointer to a valid encoder or decoder state variable. On failure, returns NULL. Prototype: in rpeltp.h ~~~~~~~~~~ Original author: ~~~~~~~~~~~~~~~~ Simao Ferraz de Campos Neto DDS/Pr11 Tel: +55-192-39-6637 CPqD/Telebras Fax: +55-192-39-6125 13088-061 Campinas SP Brazil E-mail: <simao@cpqd.ansp.br> Log of changes: ~~~~~~~~~~~~~~~ 12.Apr.94 v.1.0 created. ------------------------------------------------------------------------ */ gsm rpeltp_init() { gsm rpe_state; int gsm_compliant = 0; /* Initializa state variable */ if (!(rpe_state = gsm_create())) return ((gsm) (NULL)); /* The gsm_{en,de}code() routines may operate on a compliant mode, or * in a non-compliant, faster mode - here we use the complyant one */ (void) gsm_option(rpe_state, GSM_OPT_FAST, &gsm_compliant); return (rpe_state); } /* ................... End of rpeltp_init() ......................... */ /* ------------------------------------------------------------------------ void gsm_state *rpeltp_encode (gsm_state *rpe_state, short *inp_buf, ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ short *rpe_frame); Description: ~~~~~~~~~~~~ Process the input buffer inp_buf with left-aligned 16-bit linear-format, 2-complement samples using 13-bit resolution, i.e., the lower 3 bits of each input sample are ignored. The rpe-ltp frame buffer rpe_frame is word-oriented (16-bit samples), right-aligned i.e., the lower bits are the most significatives. They follow the sequence specified by the `parameter number' in Table 1.1 of the Rec.GSM-06.10. The input buffer has always 160 samples, and the generated frame has always 76 samples. Variables: ~~~~~~~~~~ rpe_state ... state variable initialized by a previous call to rpeltp_init() inp_buf ..... pointer to a buffer with 160 16-bit, left aligned samples rpe_frame ... pointer to a rpe-ltp encoded frame buffer. Has length of 76. The samples are 16-bit, right-aligned. Return value: ~~~~~~~~~~~~~ None. Prototype: in rpeltp.h ~~~~~~~~~~ Original author: ~~~~~~~~~~~~~~~~ Simao Ferraz de Campos Neto DDS/Pr11 Tel: +55-192-39-6637 CPqD/Telebras Fax: +55-192-39-6125 13088-061 Campinas SP Brazil E-mail: <simao@cpqd.ansp.br> Log of changes: ~~~~~~~~~~~~~~~ 12.Apr.94 v.1.0 created. ------------------------------------------------------------------------ */ void rpeltp_encode(rpe_state, inp_buf, rpe_frame) gsm rpe_state; short *inp_buf, *rpe_frame; { gsm_frame rpe_packed_frame; /* Run both and save decoded samples */ gsm_encode(rpe_state, inp_buf, rpe_packed_frame); gsm_explode(rpe_state, rpe_packed_frame, rpe_frame); } /* ................... End of rpeltp_encode() ......................... */ /* ------------------------------------------------------------------------ void gsm_state *rpeltp_decode (gsm_state *rpe_state, short *rpe_frame, ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ short *out_buf); Description: ~~~~~~~~~~~~ Decode the input rpe-ltp encoded frame buffer rpe_buf with 76 righ-aligned 16-bit samples, generating 160 decoded 16-bit, left-aligned linear 2's-complement samples with 13-bit resolution, i.e., the lower 3 bits of each input sample are zeroed. These are saved in out_buf. The rpe-ltp frame buffer rpe_frame sample has the sequence specified by the `parameter number' in Table 1.1 of the Rec.GSM-06.10. Variables: ~~~~~~~~~~ rpe_state ... state variable initialized by a previous call to rpeltp_init() rpe_frame ... pointer to a rpe-ltp encoded frame buffer. Has length of 76. The samples are 16-bit, right-aligned. out_buf ..... pointer to the decode sample's buffer with 160 16-bit, left aligned samples Return value: ~~~~~~~~~~~~~ None. Prototype: in rpeltp.h ~~~~~~~~~~ Original author: ~~~~~~~~~~~~~~~~ Simao Ferraz de Campos Neto DDS/Pr11 Tel: +55-192-39-6637 CPqD/Telebras Fax: +55-192-39-6125 13088-061 Campinas SP Brazil E-mail: <simao@cpqd.ansp.br> Log of changes: ~~~~~~~~~~~~~~~ 12.Apr.94 v.1.0 created. ------------------------------------------------------------------------ */ void rpeltp_decode(rpe_state, rpe_frame, out_buf) gsm rpe_state; short *out_buf, *rpe_frame; { gsm_frame rpe_packed_frame; /* Pack frame, run only the decoder and save the decoded samples */ gsm_implode(rpe_state, rpe_frame, rpe_packed_frame); gsm_decode(rpe_state, rpe_packed_frame, out_buf); } /* ................... End of rpeltp_decode() ......................... */ /* -------------------------- END OF RPELTP.C ------------------------ */