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The following notes apply to the branch execution times:
1. For BRA and JMP <ea> instructions, where <ea> is (d16,PC) or xxx.wl, the branch acceleration
logic of the IFP calculates the target address and begins prefetching the new path. Because the IFP
and OEP are decoupled by the FIFO instruction buffer, the execution time can vary from one to
three cycles, depending on the decoupling amount.
For all other <ea> values of the JMP instruction, the branch acceleration logic is not used, and the
execution times are fixed.
2. For BSR and JSR xxx.wl opcodes, the same branch acceleration mechanism is used to initiate the
fetch of the target instruction. Depending on the amount of decoupling between the IFP and OEP,
the resulting execution times can vary from 1 to 3 cycles.
For the remaining <ea> values for the JSR instruction, the branch acceleration logic is not used,
and the execution times are fixed.
3. For the RTS opcode, the timing depends on the prediction results of the hardware return stack:
a) If predicted correctly, 2(1/0).
b) If mispredicted, 9(1/0).
c) If not predicted, 8(1/0).
JMP
<ea>
—
5(0/0)
—
—
5(0/0)
6(0/0)
1(0/0)
—
JSR
<ea>
—
5(0/1)
—
—
5(0/1)
6(0/1)
1(0/1)
—
RTE
—
—
15(2/0)
—
—
—
—
—
RTS
—
—
2(1/0)
9(1/0)
8(1/0)
—
—
—
—
—
Table 3-20. Bcc Instruction Execution Times
Opcode
Branch Cache
Correctly Predicts
Taken
Prediction Table
Correctly Predicts
Taken
Predicted
Correctly as Not
Taken
Predicted
Incorrectly
Bcc
0(0/0)
1(0/0)
1(0/0)
8(0/0)
Table 3-19. General Branch Instruction Execution Times (continued)
Opcode
<EA>
Effective Address
Rn
(An)
(An)+
-(An)
(d16,An)
(d16,PC)
(d8,An,Xi*SF)
(d8,PC,Xi*SF)
xxx.wl
#xxx
Summary of Contents for MCF54455
Page 33: ...xxviii Freescale Semiconductor ...
Page 67: ...Freescale Semiconductor 1 ...
Page 125: ...Freescale Semiconductor 1 ...
Page 145: ...Enhanced Multiply Accumulate Unit EMAC 5 21 Freescale Semiconductor ...
Page 173: ...Cache 6 28 Freescale Semiconductor ...
Page 179: ...Static RAM SRAM 7 6 Freescale Semiconductor ...
Page 207: ...Power Management 9 16 Freescale Semiconductor ...
Page 323: ...Reset Controller Module 13 8 Freescale Semiconductor ...
Page 389: ...Pin Multiplexing and Control 16 44 Freescale Semiconductor ...
Page 575: ...PCI Bus Controller 22 58 Freescale Semiconductor ...
Page 600: ...Advanced Technology Attachment ATA Freescale Semiconductor 23 25 ...
Page 601: ...Freescale Semiconductor 1 ...
Page 842: ...I2 C Interface Freescale Semiconductor 33 16 ...
Page 843: ...Freescale Semiconductor 1 ...
Page 921: ...Revision History A 6 Freescale Semiconductor ...