Preliminary Data Sheet
February 1997
DSP1628 Digital Signal Processor
Lucent Technologies Inc.
49
5 Software Architecture
(continued)
Control Instructions
All control instructions executed unconditionally execute in two cycles, except
icall
which takes three cycles. Control
instructions executed conditionally execute in three instruction cycles. (If PC,
pt
, or
pr
point to external memory, add
programmed wait-states.) Control instructions executed unconditionally require one word of program memory, while
control instructions executed conditionally require two words. Control instructions cannot be executed from the
cache.
goto JA
goto pt
call JA
call pt
icall
return
ireturn
(goto pr)
(goto pi)
The
goto JA
and
call JA
instructions should not be placed in the last or next-to-last instruction before the boundary of a 4 Kwords page. If the
goto
or
call
is placed there, the program counter will have incremented to the next page and the jump will be to the next page, rather than to
the desired current page.
The
icall
instruction is reserved for development system use.
The above control instructions, with the exception of
ireturn
and
icall
, can be conditionally executed. For example:
if le goto 0x0345
Table 20. Replacement Table for Control Instructions
Replace
CON
Value
Meaning
mi, pl, eq, ne, gt, le, nlvs, lvc, mvs, mvc, c0ge, c0lt,
c1ge, c1lt, heads, tails, true, false, allt, allf, somet,
somef, oddp, evenp, mns1, nmns1, npint, njint, lock,
ebusy
12-bit value
See Table 21 for definitions of mnemonics.
JA
Least significant 12 bits of absolute address
within the same 4 Kwords memory section.