DSP1611/17/18/27/28/29 DIGITAL SIGNAL PROCESSOR
Information Manual
Error Correction Coprocessor (DSP1618/28 Only)
April 1998
14-18
DRAFT COPY
Lucent Technologies Inc.
(continued)
14.5.4 Traceback RAM (continued)
Programming Limitations: Although in general it is not recommended, user data as well as user code can reside
in RAM4. Also, the user code that programs the ECCP and writes the instruction register (eir) can be executed
from RAM4. However, the following programming restrictions are imposed on such blocks of code and data:
1. The location of the user code must not conflict with the addresses in RAM4 used for the storage of traceback
information. The ECCP uses RAM4's address range 0x0C00 to 2
(CL + 5)
in the soft decision mode
(i.e., if ECON.SH = 0) and the address range 0x0C00 to 2
(CL + 3)
in the hard decision mode (i.e., if
ECON.SH = 1) for the storage of traceback data where CL represents the value of the constraint length field
of the ECON register. Any user data or code in RAM4 must reside outside these address ranges.
2. Access to RAM4 data and execution of code from RAM4 can be performed only during periods of ECCP
inactivity. The only exception to this rule is the execution of ECCP instructions from RAM4. In this example,
two instructions (pt=OutofRAM4 and goto pt) are executed from RAM4 after the ECCP is started with the eir
update instruction. These two instructions cause the DSP program control (PC) register to jump outside
RAM4 for the next program instructions. The jump to memory locations outside RAM4's address range must
occur immediately after the loading of the eir instruction register, and the offset to the address places the
ECCP instructions in RAM4 below the memory segment used by the ECCP itself.
.rsect ".ram"
/* ECCP code to reside in RAM
*/
OutofRAM4:
/* This address is outside of RAM4
*/
if ebusy goto .
/* Wait for ECCP to finish
*/
...
/* Now can access ECCP and/or RAM4
*/
.=offset
/* Offset to avoid conflict with ECCP
*/
program_eccp:
...
/* Load various ECCP registers here
*/
eir=UpdateMLSE
/* Invoke ECCP instruction
*/
pt=OutofRAM4
/* Address outside RAM4
*/
goto pt
/* Jump out of RAM4
*/
Содержание DSP1611
Страница 18: ...Chapter 1 Introduction...
Страница 27: ...Chapter 2 Hardware Architecture...
Страница 52: ...Chapter 3 Software Architecture...
Страница 116: ...Chapter 4 Instruction Set...
Страница 154: ...Chapter 5 Core Architecture...
Страница 176: ...Chapter 6 External Memory Interface...
Страница 208: ...Chapter 7 Serial I O...
Страница 237: ...Chapter 8 Parallel I O DSP1617 Only...
Страница 261: ...Chapter 9 Parallel Host Interface PHIF DSP1611 18 27 28 29 Only...
Страница 275: ...Chapter 10 Bit I O Unit...
Страница 284: ...Chapter 11 JTAG Test Access Port...
Страница 306: ...Chapter 12 Timer...
Страница 313: ...Chapter 13 Bit Manipulation Unit...
Страница 325: ...Chapter 14 Error Correction Coprocessor DSP1618 28 Only...
Страница 350: ...Chapter 15 Interface Guide...
Страница 367: ...Appendix A Instruction Encoding...
Страница 379: ...Appendix B Instruction Set Summary...
Страница 381: ...aD extractz aS IM16 B 52 aD insert aS arM B 53 aD insert aS IM16 B 54 aD aS aaT B 55...
Страница 437: ...Index...