RL78/F13, F14 CHAPTER 21 INTERRUPT FUNCTIONS
R01UH0368EJ0210 Rev.2.10 1512
Dec 10, 2015
21.4.4 Interrupt servicing during division instruction
The RL78/F13 and RL78/F14 handle interrupts during the DIVHU/DIVWU instruction in order to enhance the interrupt
response when a division instruction is executed.
ï‚· When an interrupt is generated while the DIVHU/DIVWU instruction is executed, the instruction is suspended
ï‚· After the instruction is suspended, the PC indicates the next instruction after DIVHU/DIVWU
ï‚· An interrupt is generated by the next instruction
ï‚· PC-3 is saved in the stack memory to execute the DIVHU/DIVWU instruction again
Table 21-6. Normal Interrupt Processing and Interrupt Processing while Executing Division Instructions
Normal interrupt Interrupts while Executing
DIVHU/DIVWU Instruction
(SP-1)  PSW (SP-1)  PSW
(SP-2)  (PC)S (SP-2)  (PC-3)S
(SP-3)  (PC)H (SP-3)  (PC-3)H
(SP-4)  (PC)L (SP-4)  (PC-3)L
PCS  0000 PCS  0000
PCH  (Vector) PCH  (Vector)
PCL  (Vector) PCL  (Vector)
SP  SP-4 SP  SP-4
IE  0 IE  0
Caution Disable interrupts when executing the DIVHU or DIVWU instruction in an interrupt servicing routine.
Alternatively, unless they are executed in the RAM area, note that execution of a DIVHU or DIVWU
instruction is possible even with interrupts enabled as long as a NOP instruction is added immediately
after the DIVHU or DIVWU instruction in the assembly language source code. The following compilers
automatically add a NOP instruction immediately after any DIVHU or DIVWU instruction output during
the build process.
- V. 1.71 and later versions of the CA78K0R (Renesas Electronics compiler), for both C and
assembly language source code
- Service pack 1.40.6 and later versions of the EWRL78 (IAR compiler), for C language source code
- GNURL78 (KPIT compiler), for C language source code
The AX, BC, DE, and HL registers are used for DIVHU/DIVWU. For the interrupt processing, save these registers in the
stack memory.
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