IABSD.fr/src/usr.bin/sndiod/dsp.h

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• Author : ratchov
  Date : 2026-03-15 14:05:25
  Hash : 3371d951
  Message : sndiod: Factor the code to join/expand channels Move the join/expand logic to the cmap structure which is used by both playback and recording code-paths.

• usr.bin/sndiod/dsp.h

• /*	$OpenBSD: dsp.h,v 1.16 2026/03/15 14:05:25 ratchov Exp $	*/
  /*
   * Copyright (c) 2012 Alexandre Ratchov <alex@caoua.org>
   *
   * Permission to use, copy, modify, and distribute this software for any
   * purpose with or without fee is hereby granted, provided that the above
   * copyright notice and this permission notice appear in all copies.
   *
   * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
   * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
   * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
   * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
   * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
   */
  #ifndef DSP_H
  #define DSP_H
  
  #include <sys/types.h>
  #include "defs.h"
  
  /*
   * Samples are numbers in the interval [-1, 1[, note that 1, the upper
   * boundary is excluded. We represent them as signed fixed point numbers
   * of ADATA_BITS. We also assume that 2^(ADATA_BITS - 1) fits in a int.
   */
  #define ADATA_BITS			24
  #define ADATA_LE			(BYTE_ORDER == LITTLE_ENDIAN)
  #define ADATA_UNIT			(1 << (ADATA_BITS - 1))
  
  #define ADATA_MUL(x,y)		\
  	((int)(((long long)(x) * (long long)(y)) >> (ADATA_BITS - 1)))
  
  typedef int adata_t;
  
  /*
   * The FIR is sampled and stored in a table of fixed-point numbers
   * with 23 fractional bits. For convenience, we use the same fixed-point
   * numbers to represent time and to walk through the table.
   */
  #define RESAMP_BITS		23
  #define RESAMP_UNIT		(1 << RESAMP_BITS)
  
  /*
   * Filter window length (the time unit is RESAMP_UNIT)
   */
  #define RESAMP_LENGTH		(8 * RESAMP_UNIT)
  
  /*
   * Time between samples of the FIR (the time unit is RESAMP_UNIT)
   */
  #define RESAMP_STEP_BITS	(RESAMP_BITS - 6)
  #define RESAMP_STEP		(1 << RESAMP_STEP_BITS)
  
  /*
   * Maximum downsample/upsample ratio we support, must be a power of two.
   * The ratio between the max and the min sample rates is 192kHz / 4kHz = 48,
   * so we can use 64
   */
  #define RESAMP_RATIO		64
  
  /*
   * Maximum size of the encoding string (the longest possible
   * encoding is ``s24le3msb'').
   */
  #define ENCMAX	10
  
  /*
   * Default bytes per sample for the given bits per sample.
   */
  #define APARAMS_BPS(bits) (((bits) <= 8) ? 1 : (((bits) <= 16) ? 2 : 4))
  
  struct aparams {
  	unsigned int bps;		/* bytes per sample */
  	unsigned int bits;		/* actually used bits */
  	unsigned int le;		/* 1 if little endian, else be */
  	unsigned int sig;		/* 1 if signed, 0 if unsigned */
  	unsigned int msb;		/* 1 if msb justified, else lsb */
  };
  
  struct resamp {
  #define RESAMP_NCTX	(RESAMP_LENGTH / RESAMP_UNIT * RESAMP_RATIO)
  	unsigned int ctx_start;
  	adata_t ctx[NCHAN_MAX * RESAMP_NCTX];
  	int filt_cutoff, filt_step;
  	unsigned int iblksz, oblksz;
  	int diff;
  	int nch;
  };
  
  struct conv {
  	int bfirst;			/* bytes to skip at startup */
  	unsigned int bps;		/* bytes per sample */
  	unsigned int shift;		/* shift to get 32bit MSB */
  	unsigned int bias;		/* bias of unsigned samples */
  	int bnext;			/* to reach the next byte */
  	int snext;			/* to reach the next sample */
  	int nch;
  };
  
  struct cmap {
  	int istart;
  	int inext;
  	int onext;
  	int ostart;
  	int nch;
  	int join;			/* channel join factor */
  	int expand;			/* channel expand factor */
  };
  
  #define MIDI_TO_ADATA(m)	(aparams_ctltovol[m])
  extern const int aparams_ctltovol[128];
  
  void aparams_init(struct aparams *);
  int aparams_strtoenc(struct aparams *, char *);
  int aparams_enctostr(struct aparams *, char *);
  int aparams_native(struct aparams *);
  
  void resamp_getcnt(struct resamp *, int *, int *);
  void resamp_do(struct resamp *, adata_t *, adata_t *, int, int);
  void resamp_init(struct resamp *, unsigned int, unsigned int, int);
  void enc_do(struct conv *, unsigned char *, unsigned char *, int);
  void enc_sil_do(struct conv *, unsigned char *, int);
  void enc_init(struct conv *, struct aparams *, int);
  void dec_do(struct conv *, unsigned char *, unsigned char *, int);
  void dec_init(struct conv *, struct aparams *, int);
  void cmap_do(struct cmap *, adata_t *, adata_t *, int, int, int);
  void cmap_init(struct cmap *, int, int, int, int, int, int, int, int, int);
  
  #endif /* !defined(DSP_H) */