Mlib_Macrnd - Freescale Semiconductor DSP56800E User Manual

MLIB_MacRnd

2.16 MLIB_MacRnd
The MLIB_MacRnd
fractional product of two multiplicands. The round method is the round to nearest. The
function does not saturate the output. See the following equation:
2.16.1 Available versions
This function is available in the following versions:
• Fractional output - the output is the fractional portion of the result; the result is
within the range <-1 ; 1). The result may overflow.
• Accumulator output with mixed inputs - the output is the accumulator type where the
result can be out of the range <-1 ; 1). The accumulator is the accumulator type, the
multiplicands are the fractional types. The result may overflow.
The available versions of the
Function name
MLIB_MacRnd_F16
MLIB_MacRnd_F32lls
MLIB_MacRnd_F32
MLIB_MacRnd_A32ass
44
functions return the sum of the input accumulator and the rounded
Equation 14. Algorithm formula
MLIB_MacRnd
Table 2-16. Function versions
Input type
Accum. Mult. 1 Mult. 2
frac16_t frac16_t frac16_t
frac32_t frac32_t frac16_t
frac32_t frac32_t frac32_t
acc32_t frac16_t frac16_t
MLIB User's Guide, Rev. 2, 10/2015
function are shown in the following table.
Result
type
frac16_t The fractional product (of two 16-bit fractional
multiplicands), rounded to the upper 16 bits, is
added to a 16-bit fractional accumulator. The
output is within the range <-1 ; 1).
frac32_t The fractional product (of a 32-bit and 16-bit
fractional multiplicand), rounded to the upper 32
bits [16..48], is added to a 32-bit fractional
accumulator. The output is within the range <-1 ;
1).
frac32_t The fractional product (of two 32-bit fractional
multiplicands), rounded to the upper 32 bits
[32..63], is added to a 32-bit fractional
accumulator. The output is within the range <-1 ;
1).
acc32_t The fractional product (of two 16-bit fractional
multiplicands), rounded to the upper 16 bits
[16..31], is added to a 32-bit accumulator. The
output may be out of the range <-1 ; 1).
Description
Freescale Semiconductor, Inc.