From 1298bc978afba0a507cedd0a91e53267ca152804 Mon Sep 17 00:00:00 2001 From: Oswald Buddenhagen Date: Sun, 14 May 2023 19:03:22 +0200 Subject: ALSA: emu10k1: enable bit-exact playback, part 1: DSP attenuation Fractional multiplication with the maximal value 2^31-1 causes some tiny distortion. Instead, we want to multiply with the full 2^31. The catch is of course that this cannot be represented in the DSP's signed 32 bit registers. One way to deal with this is to encode 1.0 as a negative number and special-case it. As a matter of fact, the SbLive! code path already contained such code, though the controls never actually exercised it. A more efficient approach is to use negative values, which actually extend to -2^31. Accordingly, for all the volume adjustments we now use the MAC1 instruction which negates the X operand. The range of the controls in highres mode is extended downwards, so -1 is the new zero/mute. At maximal excursion, real zero is not mute any more, but I don't think anyone will notice this behavior change. ;-) That also required making the min/max/values in the control structs signed. This technically changes the user space interface, but it seems implausible that someone would notice - the numbers were actually treated as if they were signed anyway (and in the actual mixer iface they _are_). And without this change, the min value didn't even make sense in the first place (and no-one noticed, because it was always 0). Tested-by: Jonathan Dowland Signed-off-by: Oswald Buddenhagen Link: https://lore.kernel.org/r/20230514170323.3408834-7-oswald.buddenhagen@gmx.de Signed-off-by: Takashi Iwai --- include/sound/emu10k1.h | 6 +++--- include/uapi/sound/emu10k1.h | 8 +++++--- 2 files changed, 8 insertions(+), 6 deletions(-) (limited to 'include') diff --git a/include/sound/emu10k1.h b/include/sound/emu10k1.h index e9b1729ade60..8e27f7074230 100644 --- a/include/sound/emu10k1.h +++ b/include/sound/emu10k1.h @@ -1508,9 +1508,9 @@ struct snd_emu10k1_fx8010_ctl { unsigned int vcount; unsigned int count; /* count of GPR (1..16) */ unsigned short gpr[32]; /* GPR number(s) */ - unsigned int value[32]; - unsigned int min; /* minimum range */ - unsigned int max; /* maximum range */ + int value[32]; + int min; /* minimum range */ + int max; /* maximum range */ unsigned int translation; /* translation type (EMU10K1_GPR_TRANSLATION*) */ struct snd_kcontrol *kcontrol; }; diff --git a/include/uapi/sound/emu10k1.h b/include/uapi/sound/emu10k1.h index c8e131d6da00..4c32a116e7ad 100644 --- a/include/uapi/sound/emu10k1.h +++ b/include/uapi/sound/emu10k1.h @@ -308,6 +308,8 @@ struct snd_emu10k1_fx8010_info { #define EMU10K1_GPR_TRANSLATION_BASS 2 #define EMU10K1_GPR_TRANSLATION_TREBLE 3 #define EMU10K1_GPR_TRANSLATION_ONOFF 4 +#define EMU10K1_GPR_TRANSLATION_NEGATE 5 +#define EMU10K1_GPR_TRANSLATION_NEG_TABLE100 6 enum emu10k1_ctl_elem_iface { EMU10K1_CTL_ELEM_IFACE_MIXER = 2, /* virtual mixer device */ @@ -328,9 +330,9 @@ struct snd_emu10k1_fx8010_control_gpr { unsigned int vcount; /* visible count */ unsigned int count; /* count of GPR (1..16) */ unsigned short gpr[32]; /* GPR number(s) */ - unsigned int value[32]; /* initial values */ - unsigned int min; /* minimum range */ - unsigned int max; /* maximum range */ + int value[32]; /* initial values */ + int min; /* minimum range */ + int max; /* maximum range */ unsigned int translation; /* translation type (EMU10K1_GPR_TRANSLATION*) */ const unsigned int *tlv; }; -- cgit v1.2.3