Instruction Set Summary
MOTOROLA MC68030 USER’S MANUAL 3-11
3.2.8 Program Control Instructions
A set of subroutine call and return instructions and conditional and unconditional branch
instructions perform program control operations. The no operation instruction (NOP) may be
used to force synchronization of the internal pipelines. Table 3–8 summarizes these
instructions.
Letters cc in the integer instruction mnemonics Bcc, DBcc, and Scc specify testing one of the following conditions:
CC — Carry clear GE — Greater or equal
LS — Lower or same PL — Plus
CS — Carry set GT — Greater than
LT — Less than T — Always true*
EQ — Equal HI — Higher
MI — Minus VC — Overflow clear
F — Never true* LE — -Less or equal
NE — Not equal VS — Overflow set
*Not applicable to the Bcc instructions.
Table 3-8. Program Control Operations
Instruction Operand Syntax Operand Size Operation
Integer and Floating-Point Conditional
Bcc 〈label〉 8, 16, 32 if condition true, then PC + d → PC
DBcc Dn,〈label〉 16 if condition false, then Dn — 1 → Dn
if Dn ≠ -1, then PC + d → PC
Scc 〈ea〉 8 if condition true, then 1's → destination;
else 0's → destination
Unconditional
BRA 〈label〉 8, 16, 32 PC + d → PC
BSR 〈label〉 8, 16, 32 SP — 4 → SP; PC→(SP); PC + d → PC
JMP 〈ea〉 none destination → PC
JSR 〈ea〉 none SP — 4 → SP; PC→ (SP); destination → PC
NOP none none PC + 2 → PC
Returns
RTD #〈d〉 16 (SP) → PC; SP + 4 + d → SP
RTR none none (SP) → CCR; SP + 2 → SP; (SP) → PC; SP + 4 → SP
RTS none none (SP) → PC; SP + 4→ SP
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