Motorola M68000 - JMP, JSR, LEA, PEA, and MOVEM Instruction Execution Times; Multiprecision Instruction Execution Times

9- 10 M68000 8-/16-/32-BIT MICROPROCESSORS USER'S MANUAL MOTOROLA
Table 9-15. Conditional Instruction Execution Times
Instruction Displacement Branch Taken Branch Not Taken
Bcc Byte 10(2/0) 6(1/0)
Word 10(2/0) 10(2/0)
BRA Byte 10(2/0) —
Word 10(2/0) —
BSR Byte 18(2/2) —
Word 18(2/2) —
DBcc cc true — 10(2/0)
cc false 10(2/0) 16(3/0)
9.9 JMP, JSR, LEA, PEA, AND MOVEM INSTRUCTION
EXECUTION TIMES
Table 9-16 lists the timing data for the jump (JMP), jump to subroutine (JSR), load
effective address (LEA), push effective address (PEA), and move multiple registers
(MOVEM) instructions. The total number of clock periods, the number of read cycles, and
the number of write cycles are shown in the previously described format.
Table 9-16. JMP, JSR, LEA, PEA, and MOVEM Instruction Execution Times
Instruction Size (An) (An)+ –(An) (d
16
,An) (d
8
,An,Xn)+ (xxx) W (xxx).L (d
8
PC) (d
16
, PC, Xn)*
JMP — 8(2/0) — — 10 (2/0) 14 (3/0) 10 (2/0) 12 (3/0) 10 (2/0) 14 (3/0)
JSR — 16 (2/2) — — 18 (2/2) 22 (2/2) 18 (2/2) 20 (3/2) 18 (2/2) 22 (2/2)
LEA — 4(1/0) — — 8(2/0) 12 (2/0) 8(2/0) 12 (3/0) 8(2/0) 12 (2/0)
PEA — 12 (1/2) — — 16 (2/2) 20 (2/2) 16 (2/2) 20 (3/2) 16 (2/2) 20 (2/2)
MOVEM
M → R
Word 12+4n
(3+n/0)
12+4n
(3+n/0)
—
—
16+4n
(4+n/0)
18+4n
(4+n/0)
16+4n
(4+n/0)
20+4n
(5+n/0)
16+4n
(4+n/0)
18+4n
(4+n/0)
Long 24+8n
(3+2n/0)
12+8n
(3+2n/0)
—
—
16+8n
(4+2n/0)
18+8n
(4+2n/0)
16+8n
(4+2n/0)
20+8n
(5+2n/0)
16+8n
(4+2n/0)
18+8n
(4+2n/0)
MOVEM
R → M
Word 8+4n
(2/n)
—
—
8+4n
(2/n)
12+4n
(3/n)
14+4n
(3/n)
12+4n
(3/n)
16+4n
(4/n)
—
—
—
—
Long 8+8n
(2/2n)
—
—
8+8n
(2/2n)
12+8n
(3/2n)
14+8n
(3/2n)
12+8n
(3/2n)
16+8n
(4/2n)
—
—
—
—
MOVES
M → R
Byte/
Word
18 (3/0) 20 (3/0) 20 (3/0) 20 (4/0) 24 (4/0) 20 (4/0) 24 (5/0)
Long 22 (4/0) 24 (4/0) 24 (4/0) 24 (5/0) 28 (5/0) 24 (5/0) 28 (6/0)
MOVES
R → M
Byte/
Word
18 (2/1) 20 (2/1) 20 (2/1) 20 (3/1) 24 (3/1) 20 (3/1) 24 (4/1)
Long 22 (2/2) 24 (2/2) 24 (2/2) 24 (3/2) 28 (3/2) 24 (3/2) 28 (4/2)
n is the number of registers to move.
*The size of the index register (Xn) does not affect the instruction's execution time.
9.10 MULTIPRECISION INSTRUCTION EXECUTION TIMES
Table 9-17 lists the timing data for multiprecision instructions. The numbers of clock
periods include the times to fetch both operands, perform the operations, store the results,
Frees
cale Semiconductor,
I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
nc...