Data Word Formats
5-46 ADSP-21368 SHARC Processor Hardware Reference
Data Type
The
DTYPE field of the SPCTLx control registers specifies one of four data
formats (for non-multichannel operation) shown in Table 5-3. This bit
field is reserved in I
2
S and left-justified mode. In DSP serial mode, if com-
panding is selected for primary A channel, the secondary B channel
performs a zero-fill.
L
In multichannel mode, channel B looks at XDTYPE[0] only.
If DTYPE[0] = 1 sign-extend
If DTYPE[0] = 0 zero-fill
These formats are applied to serial data words loaded into the receive and
transmit buffers. Transmit data words are not zero-filled or sign-extended,
because only the significant bits are transmitted (shown in Table 5-4).
Table 5-3. DTYPE and Data Formatting (DSP Serial Mode)
DTYPE Data Formatting
00 Right-justify, zero-fill unused MSBs
01 Right-justify, sign-extend into unused MSBs
10 Compand using μ-law (primary A channels only)
11 Compand using A-law (primary A channels only)
Table 5-4. DTYPE and Data Formatting (Multichannel)
DTYPE Data Formatting
x0 Right-justify, zero-fill unused MSBs
x1 Right-justify, sign-extend into unused MSBs
0x Compand using μ-law (primary A channels only)
1x Compand using A-law (primary A channels only)
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