diff options
Diffstat (limited to 'media/libstagefright/codecs/aacdec/pv_div.cpp')
| -rw-r--r-- | media/libstagefright/codecs/aacdec/pv_div.cpp | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/media/libstagefright/codecs/aacdec/pv_div.cpp b/media/libstagefright/codecs/aacdec/pv_div.cpp new file mode 100644 index 0000000..86d2487 --- /dev/null +++ b/media/libstagefright/codecs/aacdec/pv_div.cpp @@ -0,0 +1,188 @@ +/* ------------------------------------------------------------------ + * Copyright (C) 1998-2009 PacketVideo + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * 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. + * ------------------------------------------------------------------- + */ +/* + + Filename: pv_div.c + +------------------------------------------------------------------------------ + REVISION HISTORY + + + Who: Date: MM/DD/YYYY + Description: + +------------------------------------------------------------------------------ + INPUT AND OUTPUT DEFINITIONS + + Int32 x 32-bit integer numerator + Int32 y 32-bit integer denominator + Quotient *result structure that hold result and shift factor + + +------------------------------------------------------------------------------ + FUNCTION DESCRIPTION + + Implement division of two Int32 numbers, provides back quotient and a + shift factor +------------------------------------------------------------------------------ + REQUIREMENTS + + +------------------------------------------------------------------------------ + REFERENCES + +------------------------------------------------------------------------------ + PSEUDO-CODE + +------------------------------------------------------------------------------ +*/ + + +/*---------------------------------------------------------------------------- +; INCLUDES +----------------------------------------------------------------------------*/ +#ifdef AAC_PLUS + + +#include "pv_audio_type_defs.h" +#include "fxp_mul32.h" +#include "pv_div.h" +#include "pv_normalize.h" + +/*---------------------------------------------------------------------------- +; MACROS +; Define module specific macros here +----------------------------------------------------------------------------*/ + + +/*---------------------------------------------------------------------------- +; DEFINES +; Include all pre-processor statements here. Include conditional +; compile variables also. +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; LOCAL FUNCTION DEFINITIONS +; Function Prototype declaration +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; LOCAL STORE/BUFFER/POINTER DEFINITIONS +; Variable declaration - defined here and used outside this module +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; EXTERNAL FUNCTION REFERENCES +; Declare functions defined elsewhere and referenced in this module +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES +; Declare variables used in this module but defined elsewhere +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; FUNCTION CODE +----------------------------------------------------------------------------*/ + + +void pv_div(Int32 x, Int32 y, Quotient *result) +{ + /*---------------------------------------------------------------------------- + ; Define all local variables + ----------------------------------------------------------------------------*/ + Int32 quotient; + Int32 i; + Int32 j; + Int32 y_ov_y_hi; + Int32 flag = 0; /* carries negative sign, if any */ + + + result->shift_factor = 0; /* default */ + + if (y == 0) + { + x = 0; /* this will return 0 for any div/0 */ + } + /* + * make sure x and y are both positive + */ + + if (y < 0) + { + y = -y; + flag ^= 1; + } + + + if (x < 0) + { + x = -x; + flag ^= 1; + } + + if (x != 0) + { + /*---------------------------------------------------------------------------- + ; Scale the input to get maximum precision for x + ----------------------------------------------------------------------------*/ + + i = pv_normalize(x); + + x <<= i; + + + /*---------------------------------------------------------------------------- + ; Scale the input to get maximum precision for y + ----------------------------------------------------------------------------*/ + + j = pv_normalize(y); + + y <<= j; + + result->shift_factor = i - j; + + /*---------------------------------------------------------------------------- + ; Function body here + ----------------------------------------------------------------------------*/ + /*--------------------------------------------------------------- + ; take the inverse of the 16 MSB of y + ---------------------------------------------------------------*/ + + quotient = (0x40000000 / (y >> 15)); + + y_ov_y_hi = fxp_mul32_Q15(y, quotient); /* y*(1/y_hi) */ + + y_ov_y_hi = 0x7FFFFFFF - y_ov_y_hi; /* 2 - y*(1/y_hi) */ + y_ov_y_hi = fxp_mul32_Q14(quotient, y_ov_y_hi); + i = fxp_mul32_Q31(y_ov_y_hi, x) << 1; + + result->quotient = flag ? -i : i; + } + else + { + result->quotient = 0; + } + + + +} + +#endif + + |