Commit 4c7bfbcf authored by Oswald Buddenhagen's avatar Oswald Buddenhagen Committed by Takashi Iwai
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ALSA: emu10k1: simplify snd_emu10k1_audigy_dsp_convert_32_to_2x16() 



Instead of spending lots of instructions on masking and transplanting
the sign bit, sidestep the issue by replacing the last bit shift with
a wrapping addition to self.

Solution stolen from kX-project, after I pondered other ideas first.

Also, the function really doesn't need to return a constant int value.

Signed-off-by: default avatarOswald Buddenhagen <oswald.buddenhagen@gmx.de>
Link: https://lore.kernel.org/r/20230510173917.3073107-5-oswald.buddenhagen@gmx.de


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 4102ac29

sound/pci/emu10k1/emufx.c

+13 −13
Original line number Diff line number Diff line
@@ -1184,20 +1184,22 @@ snd_emu10k1_init_stereo_onoff_control(struct snd_emu10k1_fx8010_control_gpr *ctl 
 * to 2 x 16-bit registers in Audigy - their values are read via DMA.

 * Conversion is performed by Audigy DSP instructions of FX8010.

 */

static int snd_emu10k1_audigy_dsp_convert_32_to_2x16(

static void snd_emu10k1_audigy_dsp_convert_32_to_2x16(

				struct snd_emu10k1_fx8010_code *icode,

				u32 *ptr, int tmp, int bit_shifter16,

				int reg_in, int reg_out)

{

	A_OP(icode, ptr, iACC3, A_GPR(tmp + 1), reg_in, A_C_00000000, A_C_00000000);

	A_OP(icode, ptr, iANDXOR, A_GPR(tmp), A_GPR(tmp + 1), A_GPR(bit_shifter16 - 1), A_C_00000000);

	A_OP(icode, ptr, iTSTNEG, A_GPR(tmp + 2), A_GPR(tmp), A_C_80000000, A_GPR(bit_shifter16 - 2));

	A_OP(icode, ptr, iANDXOR, A_GPR(tmp + 2), A_GPR(tmp + 2), A_C_80000000, A_C_00000000);

	A_OP(icode, ptr, iANDXOR, A_GPR(tmp), A_GPR(tmp), A_GPR(bit_shifter16 - 3), A_C_00000000);

	A_OP(icode, ptr, iMACINT0, A_GPR(tmp), A_C_00000000, A_GPR(tmp), A_C_00010000);

	A_OP(icode, ptr, iANDXOR, reg_out, A_GPR(tmp), A_C_ffffffff, A_GPR(tmp + 2));

	A_OP(icode, ptr, iACC3, reg_out + 1, A_GPR(tmp + 1), A_C_00000000, A_C_00000000);

	return 1;

	// This leaves the low word in place, which is fine,

	// as the low bits are completely ignored subsequently.

	// reg_out[1] = reg_in

	A_OP(icode, ptr, iACC3, reg_out + 1, reg_in, A_C_00000000, A_C_00000000);

	// It is fine to read reg_in multiple times.

	// tmp = reg_in << 15

	A_OP(icode, ptr, iMACINT1, A_GPR(tmp), A_C_00000000, reg_in, A_GPR(bit_shifter16));

	// Left-shift once more. This is a separate step, as the

	// signed multiplication would clobber the MSB.

	// reg_out[0] = tmp + ((tmp << 31) >> 31)

	A_OP(icode, ptr, iMAC3, reg_out, A_GPR(tmp), A_GPR(tmp), A_C_80000000);

}



/*
@@ -1247,10 +1249,8 @@ static int _snd_emu10k1_audigy_init_efx(struct snd_emu10k1 *emu) 
	ptr = 0;

	nctl = 0;

	gpr = stereo_mix + 10;

	gpr_map[gpr++] = 0x00007fff;

	gpr_map[gpr++] = 0x00008000;

	gpr_map[gpr++] = 0x0000ffff;

	bit_shifter16 = gpr;

	gpr_map[gpr++] = 0x00008000;



#if 1

	/* PCM front Playback Volume (independent from stereo mix)