Normal Word (32-Bit) Accesses; Short Word (16-Bit) Accesses - Analog Devices ADSP-21261 SHARC Hardware Reference Manual

Accessing Memory
The DSP transfers the 40-bit data to internal memory as a 48-bit value,
zero-filling the least significant 8 bits on stores and truncating these 8 bits
on loads. The register file source or destination of such an access is a single
40-bit data register.

Normal Word (32-Bit) Accesses

A program makes a normal word (32-bit) access to internal memory using
an access to a normal word address when that internal memory block's
bit is cleared (=0) for 32-bit words. Programs use normal word
IMDWx
addressing to access all DSP memory spaces. The address ranges for mem-
ory accesses appear in
and Figure 5-11 on page
The register file source or destination of a normal word access is a single
40-bit data register. The DSP zero-fills the least significant 8 bits on loads
and truncates these bits on stores.

Short Word (16-Bit) Accesses

A program makes a short word (16-bit) access to internal memory using
an access to a short word address. The address ranges for internal memory
accesses appear in
The register file source or destination of such an access is a single 40-bit
data register. The DSP zero-fills the least significant 8 bits on loads and
truncates these bits on stores. Depending on the value of the
system register, the DSP loads the register's upper 16 bits by either:
MODE1
• Zero-filling these bits if
• Sign-extending these bits if
5-26
Figure 5-8 on page
5-33.
Figure 5-8 on page
=0
SSE
SSE
ADSP-2126x SHARC Processor Hardware Reference
5-14, Figure 5-10 on page
5-14.
=1
5-15,
bit in the
SSE