
49
CHAPTER 3 MEMORY SPACE, CPU AND CONTROL UNIT
3.7.1
Operations with Delay Slots
During operations with delay slots, a branch occurs at an instruction immediately after
a branch instruction (called a delay slot) before the branch destination instruction is
executed.
■
Branch instructions with delay slots
The following branch instructions with delay slots are provided:
■
Explanation of the operation of branch instructions with delay slots
During operation with delay slots, a branch occurs after an instruction immediately after the
branch instruction (called a delay slot) is executed before a branch destination instruction is
executed.
A delay slot instruction is executed before the branch operation. Consequently, the execution
speed appears to be one cycle. If an effective instruction cannot be placed in a delay slot, the
NOP instruction must be placed instead.
[Example]
In a conditional branch instruction, an instruction placed in a delay slot is executed regardless of
whether a branch condition is met.
For the delayed branch instruction, the execution order of some instructions appears to be
reversed. However, this appearance of reversal applies only for the PC update operation. In
other operations (register update and reference, etc.), the instructions are executed in the
specified order.
A specific example is given below.
JMP:D @Ri CALL:D label12 CALL:D @Ri RET:D
BRA:D label9 BNO:D label9 BEQ:D label9 BNE:D label9
BC:D label9 BNC:D label9 BN:D label9 BP:D label9
BV:D label9 BNV:D label9 BLT:D label9 BGE:D label9
BLE:D label9 BGT:D label9 BLS:D label9 BHI:D label9
; Instruction list
ADD R1, R2 ;
BRA:D LABEL ; Branch instruction
MOV R2, R3 ; Delay slot: Executed before a branch.
...
LABEL : STR3, @R4 ; Branch destination
Содержание MB91150 Series
Страница 1: ......
Страница 2: ......
Страница 3: ...FUJITSU LIMITED FR30 32 BIT MICROCONTROLLER MB91150 Series HARDWARE MANUAL ...
Страница 4: ......
Страница 10: ...vi ...
Страница 112: ...96 CHAPTER 3 MEMORY SPACE CPU AND CONTROL UNIT ...
Страница 174: ...158 CHAPTER 5 I O PORTS Note DDRI bit 6 is a test bit Always set the bit to 0 The value read from this bit is always 0 ...
Страница 178: ...162 CHAPTER 5 I O PORTS ...
Страница 214: ...198 CHAPTER 7 16 BIT RELOAD TIMER ...
Страница 240: ...224 CHAPTER 8 PPG TIMER ...
Страница 310: ...294 CHAPTER 13 8 10 BIT A D CONVERTER ...
Страница 318: ...302 CHAPTER 14 8 BIT D A CONVERTER ...
Страница 362: ...346 CHAPTER 15 UART ...
Страница 420: ...404 CHAPTER 19 PERIPHERAL STOP CONTROL ...
Страница 428: ...412 CHAPTER 20 CALENDAR MACROS ...
Страница 503: ...487 INDEX INDEX The index follows on the next page This is listed in alphabetic order ...
Страница 510: ...494 INDEX ...
Страница 512: ......