diff options
Diffstat (limited to 'arm-wt-22k/lib_src/eas_math.c')
-rw-r--r-- | arm-wt-22k/lib_src/eas_math.c | 312 |
1 files changed, 156 insertions, 156 deletions
diff --git a/arm-wt-22k/lib_src/eas_math.c b/arm-wt-22k/lib_src/eas_math.c index 12d788e..dc85051 100644 --- a/arm-wt-22k/lib_src/eas_math.c +++ b/arm-wt-22k/lib_src/eas_math.c @@ -1,13 +1,13 @@ -/*----------------------------------------------------------------------------
- *
- * File:
- * eas_math.c
- *
- * Contents and purpose:
- * Contains common math routines for the various audio engines.
- *
- *
- * Copyright Sonic Network Inc. 2005
+/*---------------------------------------------------------------------------- + * + * File: + * eas_math.c + * + * Contents and purpose: + * Contains common math routines for the various audio engines. + * + * + * Copyright Sonic Network Inc. 2005 * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -20,149 +20,149 @@ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. - *
- *----------------------------------------------------------------------------
- * Revision Control:
- * $Revision: 586 $
- * $Date: 2007-03-08 20:33:04 -0800 (Thu, 08 Mar 2007) $
- *----------------------------------------------------------------------------
-*/
-
-#include "eas.h"
-#include "eas_math.h"
-
-/* anything less than this converts to a fraction too small to represent in 32-bits */
-#define MIN_CENTS -18000
-
-/*----------------------------------------------------------------------------
- * EAS_Calculate2toX()
- *----------------------------------------------------------------------------
- * Purpose:
- * Calculate 2^x
- *
- * Inputs:
- * nCents - measured in cents
- * psEASData - pointer to overall EAS data structure
- *
- * Outputs:
- * nResult - int.frac result (where frac has NUM_DENTS_FRAC_BITS)
- *
- * Side Effects:
- *
- *----------------------------------------------------------------------------
-*/
-EAS_I32 EAS_Calculate2toX (EAS_I32 nCents)
-{
- EAS_I32 nDents;
- EAS_I32 nExponentInt, nExponentFrac;
- EAS_I32 nTemp1, nTemp2;
- EAS_I32 nResult;
-
- /* check for minimum value */
- if (nCents < MIN_CENTS)
- return 0;
-
- /* for the time being, convert cents to dents */
- nDents = FMUL_15x15(nCents, CENTS_TO_DENTS);
-
- nExponentInt = GET_DENTS_INT_PART(nDents);
- nExponentFrac = GET_DENTS_FRAC_PART(nDents);
-
- /*
- implement 2^(fracPart) as a power series
- */
- nTemp1 = GN2_TO_X2 + MULT_DENTS_COEF(nExponentFrac, GN2_TO_X3);
- nTemp2 = GN2_TO_X1 + MULT_DENTS_COEF(nExponentFrac, nTemp1);
- nTemp1 = GN2_TO_X0 + MULT_DENTS_COEF(nExponentFrac, nTemp2);
-
- /*
- implement 2^(intPart) as
- a left shift for intPart >= 0 or
- a left shift for intPart < 0
- */
- if (nExponentInt >= 0)
- {
- /* left shift for positive exponents */
- /*lint -e{703} <avoid multiply for performance>*/
- nResult = nTemp1 << nExponentInt;
- }
- else
- {
- /* right shift for negative exponents */
- nExponentInt = -nExponentInt;
- nResult = nTemp1 >> nExponentInt;
- }
-
- return nResult;
-}
-
-/*----------------------------------------------------------------------------
- * EAS_LogToLinear16()
- *----------------------------------------------------------------------------
- * Purpose:
- * Transform log value to linear gain multiplier using piece-wise linear
- * approximation
- *
- * Inputs:
- * nGain - log scale value in 20.10 format. Even though gain is normally
- * stored in 6.10 (16-bit) format we use 32-bit numbers here to eliminate
- * the need for saturation checking when combining gain values.
- *
- * Outputs:
- * Returns a 16-bit linear value approximately equal to 2^(nGain/1024)
- *
- * Side Effects:
- *
- *----------------------------------------------------------------------------
-*/
-EAS_U16 EAS_LogToLinear16 (EAS_I32 nGain)
-{
- EAS_INT nExp;
- EAS_U16 nTemp;
-
- /* bias to positive */
- nGain += 32767;
-
- /* check for infinite attenuation */
- if (nGain < 0)
- return 0;
-
- /* extract the exponent */
- nExp = 31 - (nGain >> 10);
-
- /* check for maximum output */
- if (nExp < 0)
- return 0x7fff;
-
- /* extract mantissa and restore implied 1 bit */
- nTemp = (EAS_U16)((((nGain & 0x3ff) << 4) | 0x4000) >> nExp);
-
- /* use shift to approximate power-of-2 operation */
- return nTemp;
-}
-
-/*----------------------------------------------------------------------------
- * EAS_VolumeToGain()
- *----------------------------------------------------------------------------
- * Purpose:
- * Transform volume control in 1dB increments to gain multiplier
- *
- * Inputs:
- * volume - 100 = 0dB, 99 = -1dB, 0 = -inf
- *
- * Outputs:
- * Returns a 16-bit linear value
- *----------------------------------------------------------------------------
-*/
-EAS_I16 EAS_VolumeToGain (EAS_INT volume)
-{
- /* check for limits */
- if (volume <= 0)
- return 0;
- if (volume >= 100)
- return 0x7fff;
-
- /*lint -e{702} use shift instead of division */
- return (EAS_I16) EAS_Calculate2toX((((volume - EAS_MAX_VOLUME) * 204099) >> 10) - 1);
-}
-
+ * + *---------------------------------------------------------------------------- + * Revision Control: + * $Revision: 586 $ + * $Date: 2007-03-08 20:33:04 -0800 (Thu, 08 Mar 2007) $ + *---------------------------------------------------------------------------- +*/ + +#include "eas.h" +#include "eas_math.h" + +/* anything less than this converts to a fraction too small to represent in 32-bits */ +#define MIN_CENTS -18000 + +/*---------------------------------------------------------------------------- + * EAS_Calculate2toX() + *---------------------------------------------------------------------------- + * Purpose: + * Calculate 2^x + * + * Inputs: + * nCents - measured in cents + * psEASData - pointer to overall EAS data structure + * + * Outputs: + * nResult - int.frac result (where frac has NUM_DENTS_FRAC_BITS) + * + * Side Effects: + * + *---------------------------------------------------------------------------- +*/ +EAS_I32 EAS_Calculate2toX (EAS_I32 nCents) +{ + EAS_I32 nDents; + EAS_I32 nExponentInt, nExponentFrac; + EAS_I32 nTemp1, nTemp2; + EAS_I32 nResult; + + /* check for minimum value */ + if (nCents < MIN_CENTS) + return 0; + + /* for the time being, convert cents to dents */ + nDents = FMUL_15x15(nCents, CENTS_TO_DENTS); + + nExponentInt = GET_DENTS_INT_PART(nDents); + nExponentFrac = GET_DENTS_FRAC_PART(nDents); + + /* + implement 2^(fracPart) as a power series + */ + nTemp1 = GN2_TO_X2 + MULT_DENTS_COEF(nExponentFrac, GN2_TO_X3); + nTemp2 = GN2_TO_X1 + MULT_DENTS_COEF(nExponentFrac, nTemp1); + nTemp1 = GN2_TO_X0 + MULT_DENTS_COEF(nExponentFrac, nTemp2); + + /* + implement 2^(intPart) as + a left shift for intPart >= 0 or + a left shift for intPart < 0 + */ + if (nExponentInt >= 0) + { + /* left shift for positive exponents */ + /*lint -e{703} <avoid multiply for performance>*/ + nResult = nTemp1 << nExponentInt; + } + else + { + /* right shift for negative exponents */ + nExponentInt = -nExponentInt; + nResult = nTemp1 >> nExponentInt; + } + + return nResult; +} + +/*---------------------------------------------------------------------------- + * EAS_LogToLinear16() + *---------------------------------------------------------------------------- + * Purpose: + * Transform log value to linear gain multiplier using piece-wise linear + * approximation + * + * Inputs: + * nGain - log scale value in 20.10 format. Even though gain is normally + * stored in 6.10 (16-bit) format we use 32-bit numbers here to eliminate + * the need for saturation checking when combining gain values. + * + * Outputs: + * Returns a 16-bit linear value approximately equal to 2^(nGain/1024) + * + * Side Effects: + * + *---------------------------------------------------------------------------- +*/ +EAS_U16 EAS_LogToLinear16 (EAS_I32 nGain) +{ + EAS_INT nExp; + EAS_U16 nTemp; + + /* bias to positive */ + nGain += 32767; + + /* check for infinite attenuation */ + if (nGain < 0) + return 0; + + /* extract the exponent */ + nExp = 31 - (nGain >> 10); + + /* check for maximum output */ + if (nExp < 0) + return 0x7fff; + + /* extract mantissa and restore implied 1 bit */ + nTemp = (EAS_U16)((((nGain & 0x3ff) << 4) | 0x4000) >> nExp); + + /* use shift to approximate power-of-2 operation */ + return nTemp; +} + +/*---------------------------------------------------------------------------- + * EAS_VolumeToGain() + *---------------------------------------------------------------------------- + * Purpose: + * Transform volume control in 1dB increments to gain multiplier + * + * Inputs: + * volume - 100 = 0dB, 99 = -1dB, 0 = -inf + * + * Outputs: + * Returns a 16-bit linear value + *---------------------------------------------------------------------------- +*/ +EAS_I16 EAS_VolumeToGain (EAS_INT volume) +{ + /* check for limits */ + if (volume <= 0) + return 0; + if (volume >= 100) + return 0x7fff; + + /*lint -e{702} use shift instead of division */ + return (EAS_I16) EAS_Calculate2toX((((volume - EAS_MAX_VOLUME) * 204099) >> 10) - 1); +} + |