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- Name: LINLOG.ASM
- Type: Assembler Macros
- Version: 1.0
- Date Entered: 20-Apr-87
- Last Change: 20-Apr-87
-
- Description: Linear PCM to Companded CODEC Data Conversion Macros
-
- These macros convert 13 bit, linear fractional data into 8 bit companded
- data suitable for transmission to CODEC D/A converters used in
- telecommunications applications. Four companded formats are
- supported for the Motorola MC14400 CODEC series and similar devices.
-
-
-
- Macro Name Description
- ---------- -----------
- linsm linear to sign magnitude conversion with mu-law companding.
-
- linmu linear to mu-law companded conversion without zero code
- suppression.
-
- lind3d4 linear to mu-law companded conversion with D3/D4 format
- zero code suppression.
-
- linal linear to a-law companded conversion with CCITT (G7.12)
- format.
-
- Input data is a 56 bit number in accumulator a. Although any 56 bit
- number may be used, the 13 bit linear fraction is assumed to be in
- the most significant bits of a1. Values outside this fractional range
- are automatically converted to a maximum positive or negative companded
- value (dynamic range limiting).
-
- Output data is in the 8 most significant bits of a1. The 16 LSB's
- of a1 are zero.
-
- -------------------------------------------------------
- | Sign | Chord Number | Step Number |
- | Bit | | |
- |__23__|__22_____21_____20__|__19_____18_____17_____16__|
-
- These macros execute in 23-25 instruction cycles worst case and require
- 16-18 words of program memory. They do not use the DSP56001 internal
- mu/a-law lookup table.
-