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: Oswald Buddenhagen oswald.buddenhagen@gmx.de --- sound/pci/emu10k1/emufx.c | 26 +++++++++++++------------- 1 file changed, 13 insertions(+), 13 deletions(-)
diff --git a/sound/pci/emu10k1/emufx.c b/sound/pci/emu10k1/emufx.c index 795b2573fef4..8ba294138dfe 100644 --- a/sound/pci/emu10k1/emufx.c +++ b/sound/pci/emu10k1/emufx.c @@ -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)