1 /* Copyright (c) 2012 The Chromium OS Authors. All rights reserved. 2 * Use of this source code is governed by a BSD-style license that can be 3 * found in the LICENSE file. 4 */ 5 6 #ifndef CRAS_VOLUME_CURVE_H_ 7 #define CRAS_VOLUME_CURVE_H_ 8 9 #define MAX_VOLUME 100 10 #define NUM_VOLUME_STEPS (MAX_VOLUME + 1) /* 0-100 inclusive. */ 11 12 /* Holds the function that converts from a volume index to a dBFS value. */ 13 struct cras_volume_curve { 14 /* Function to convert from index to dBFS value. 15 * Args: 16 * curve - A curve from cras_volume_curve_create_* functions. 17 * volume - The volume level from 0 to 100. 18 * Returns: 19 * The volume to apply in dB * 100. This value will normally be 20 * negative and is means dB down from full scale. 21 */ 22 long (*get_dBFS)(const struct cras_volume_curve *curve, size_t volume); 23 }; 24 25 /* Creates a system-default volume curve. The default curve maps one volume step 26 * to 1 dB down. 27 * Returns null on error, or the new volume curve on success. 28 */ 29 struct cras_volume_curve *cras_volume_curve_create_default(); 30 31 /* Creates a volume curve with a specified max volume and step. 32 * Args: 33 * max_volume - Maximum volume allowed in dBFS. 34 * volume_step - Number of dB to change for one volume tick. 35 */ 36 struct cras_volume_curve *cras_volume_curve_create_simple_step( 37 long max_volume, 38 long volume_step); 39 40 /* Creates a volume curve with each step's dB value called out. 41 * Args: 42 * dB_values - Each element specifies what the volume should be set to (in 43 * dB) for the volume at that index. 44 * Returns: 45 * A volume curve pointer that should be passed to 46 * cras_volume_curve_destroy() when it is no longer needed. If there is an 47 * error NULL will be returned. 48 */ 49 struct cras_volume_curve *cras_volume_curve_create_explicit( 50 long dB_values[101]); 51 52 /* Destroys a curve created with cras_volume_curve_create_*. 53 * Args: 54 * curve - The curve to destroy. 55 */ 56 void cras_volume_curve_destroy(struct cras_volume_curve *curve); 57 58 #endif /* CRAS_VOLUME_CURVE_H_ */ 59
