ADSP-2126x SHARC Processor Hardware Reference
5-11
Memory
The ADSP-2126x has two blocks of RAM that contain up to 1M bit of
memory each, and two blocks of ROM that contain up to 2M bits of
memory each. Each block is physically comprised of four 16-bit columns.
“Wrapping”, as shown in
, allows the memory to
efficiently store 16-bit, 32-bit, 48-bit or 64-bit wide words. The width of
the data word fetched from memory is dependent upon the address range
used. The same physical location in memory can be accessed using three
different addresses.
Accessing a short word memory address accesses one 16-bit word. Consec-
utive 16-bit short-words are accessed from columns #1, #2, #3, #4, #1 and
so on. Accessing a normal word memory address transfers 32 bits (from
columns 1 and 2 or 3 and 4). Consecutive 32-bit words are accessed from
columns 1 and 2, 3 and 4, 1 and 2 etc. Accessing a long word address
transfers 64 bits (from all four columns). For example, the same 16 bits of
Block-0 are overwritten in each of the following four write instructions
(some, but not all of the short word accesses overwrite more than 16 bits).
Listing 5-1. Overwriting Bits (ADSP-21262 Example)
#include <def2126x.h>
DM(0x00040000) = PX; /* long word transfer
(64 bits/four columns)
*/
DM(0x00080000) = R0; /* normal word transfer
(32 bits/two columns)
*/
DM(0x00100000) = R0; /* short word transfer
(16 bits/1-column)
*/
NOP
USTAT1 = dm(SYSCTL);
bit set USTAT1 IMDW0; /* set Blk0 access as ext. precision
*/
dm(SYSCTL) = USTAT1;
DM(0x00080000) = R0; /* normal word transfer
(40 bits/three columns)
*/
Содержание ADSP-21261 SHARC
Страница 30: ...Contents xxx ADSP 2126x SHARC Processor Hardware Reference ...
Страница 40: ...Register Diagram Conventions xl ADSP 2126x SHARC Processor Hardware Reference ...
Страница 58: ...Differences From Previous SHARCs 1 18 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 112: ...Secondary Processing Element PEy 2 54 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 178: ...Summary 3 66 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 204: ...DAG Instruction Summary 4 26 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 322: ...Setting Up DMA 7 32 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 436: ...SPORT Programming Examples 9 86 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 521: ...ADSP 2126x SHARC Processor Hardware Reference 11 31 Input Data Port rts IDP_ISR end ...
Страница 522: ...Input Data Port Programming Example 11 32 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 590: ...Timer Programming Examples 14 20 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 796: ...I O Processor Registers A 174 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 800: ...B 4 ADSP 2126x SHARC Processor Core Manual ...
Страница 846: ...Index I 36 ADSP 2126x SHARC Processor Hardware Reference ...