Lucent Technologies DSP1611, Information Manual, Page: 129 / 443

DSP1611/17/18/27/28/29 DIGITAL SIGNAL PROCESSOR Information Manual
Instruction Set April 1998
4-12
DRAFT COPY
Lucent Technologies Inc.
4.5 Instruction Set
(continued)
4.5.1 Control Instructions
Control instructions implement goto, call, and return commands. There is no latency when branching, i.e., the
instruction executed following the control instruction has the address specified in the PC after execution of the con-
trol instruction. Control instructions are executed either conditionally or unconditionally. Both the condition and its
complement are available for use in control instructions. Control instructions can not be executed in the cache.
Control instructions can be conditioned on the basis of the DSP flags defined in Table 4-3 . The result of the most
recent accumulator operation prior to the control instruction establishes the state of the flags for the conditions
associated with logical or mathematical functions.
Table 4-4 lists the control instructions along with a description of
how each instruction is encoded, the number of instruction cycles required to execute each instruction, and the
number of memory locations (in words) required for the encoding of each instruction.
Table 4-5 describes the
replacements for the upper-case fields shown in Table 4-4 .
Table 4-4. Control Instructions
†
† Control instructions cannot be used in the cache. Table 4-5 lists replacements for the upper-case fields shown in this table.
Control Instruction Equivalent Instruction
(if applicable)
Encoded As Number of
Cycles
Number of
Words
goto JA
‡
goto pt
§
call JA
‡
call pt
§
return
§
‡ 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 Kword
page. If the goto or call is placed there, the program counter increments to the next page and the jump is to the next page rather than
the desired current page.
§ If PC, pt, or pr point to external memory, add programmed wait-states to the number of cycles.
goto pr goto JA
goto B
call JA
goto B
goto B 2 1
if CON goto JA
‡
if CON goto pt
§
if CON call JA
‡
if CON call pt
§
if CON return §
if CON goto pr if CON goto JA
if CON goto B
if CON call JA
if CON goto B
if CON goto B 3 2
ireturn goto pi goto B 2 1
icall
††
†† The icall instruction is reserved for use by the hardware development system.
icall 3 1
Table 4-5. Replacement Table for Control Function Instructions
Replace Value Meaning
CON mi, pl, eq, ne, gt, le, lvs, mvs, mvc, c0ge, c0lt,
c1ge, c1lt, heads, tails, true, false, npint, njint,
lock
†
, ebusy
‡
† DSP1627/28/29 only.
‡ DSP1618/28 only.
See Table 4-3 for definitions of processor flags.
JA 12-bit value Least significant 12 bits of an absolute address
within the same 4 Kword memory section.
B 3-bit value in B-field instruction B selects one of
return (same as goto pr)
ireturn (same as goto pi)
goto pt
call pt