7e43b2a679
The mixer API variables are declared in a header with no explicit linkage. This results in there being definitions of them in multiple object files, which causes a link failure with GCC 10, since this uses -fno-common by default. Add `extern` to the header declarations and separate declarations with no linkage in mixer.c where they are assigned. Link: https://bugs.debian.org/957947 Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
83 lines
3.7 KiB
C
83 lines
3.7 KiB
C
/* WMix 3.0 -- a mixer using the OSS mixer API.
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* Copyright (C) 2000, 2001
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* Daniel Richard G. <skunk@mit.edu>,
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* timecop <timecop@japan.co.jp>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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/* WMVolume mixer interface
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*
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* Some notes:
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*
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* - The volume argument is a floating-point value between 0 (no sound) and
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* 1 (full sound) inclusively.
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*
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* - The balance argument is a floating-point value betwen -1 (full left)
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* and 1 (full right) inclusively. A value of 0 indicates centered sound.
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* If the device does not natively support a balance parameter, use the
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* lr_to_vb() and vb_to_lr() functions in misc.c.
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*
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* - The volume and balance arguments passed to these functions, given that
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* they are (usually 32-bit) floating-point values, may be capable of
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* specifying the audio parameters at a finer resolution than the
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* hardware itself. However, the mixer driver must not quantize the
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* volume and balance levels returned by the mixer_get_*() routines.
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*
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* Example: Suppose the mixer device supports specifying the volume as an
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* integer in the range of 0 to 100. If mixer_set_volume() is called with
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* an argument of 0.7351, then the device will be set to a volume of 74,
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* yet subsequent calls to mixer_get_volume() (assuming mixer state has
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* not changed since) will return 0.7351. Only if the mixer state is
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* changed by another program (that, say, sets the volume to 51) is the
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* value returned by this interface quantized (in such a case returning
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* 0.51).
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*
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* The reason why this quantization must be avoided whenever possible is
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* that otherwise, a large number of minuscule increases to the volume
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* level will have no cumulative effect. Calling mixer_set_volume_rel()
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* ten thousand times with an argument of 0.0001 should successfully
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* increase the volume to its maximum, even if the device actually
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* supports only 64 discrete volume levels.
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*
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* - Muting must occur independently of the volume level.
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*/
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extern void (*mixer_init)(const char *mixer_device,
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bool verbose,
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const char *exclude[]);
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extern bool (*mixer_is_changed)(void);
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extern int (*mixer_get_channel_count)(void);
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extern int (*mixer_get_channel)(void);
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extern const char *(*mixer_get_channel_name)(void);
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extern const char *(*mixer_get_short_name)(void);
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extern void (*mixer_set_channel)(int channel);
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extern void (*mixer_set_channel_rel)(int delta_channel);
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extern float (*mixer_get_volume)(void);
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extern void (*mixer_set_volume)(float volume);
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extern void (*mixer_set_volume_rel)(float delta_volume);
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extern float (*mixer_get_balance)(void);
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extern void (*mixer_set_balance)(float balance);
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extern void (*mixer_set_balance_rel)(float delta_balance);
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extern void (*mixer_toggle_mute)(void);
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extern void (*mixer_toggle_rec)(void);
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extern bool (*mixer_is_muted)(void);
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extern bool (*mixer_is_stereo)(void);
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extern bool (*mixer_is_rec)(void);
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extern bool (*mixer_can_rec)(void);
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extern bool (*is_exclude)(const char *short_name,
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const char *exclude[]);
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extern void (*mixer_tick)(void);
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