INSTRUCTION SET
S3C80A5B
6-38
DIV
—
Divide (Unsigned)
DIV
dst,src
Operation:
dst ÷ src
dst (UPPER)
←
REMAINDER
dst (LOWER)
←
QUOTIENT
The destination operand (16 bits) is divided by the source operand (8 bits). The quotient (8 bits) is
stored in the lower half of the destination. The remainder (8 bits) is stored in the upper half of the
destination. When the quotient is
≥
2
8
, the numbers stored in the upper and lower halves of the
destination for quotient and remainder are incorrect. Both operands are treated as unsigned
integers.
Flags:
C:
Set if the V flag is set and quotient is between 2
8
and 2
9
–1; cleared otherwise.
Z:
Set if divisor or quotient = "0"; cleared otherwise.
S:
Set if MSB of quotient = "1"; cleared otherwise.
V:
Set if quotient is
≥
2
8
or if divisor = "0"; cleared otherwise.
D:
Unaffected.
H:
Unaffected.
Format:
Bytes
Cycles
Opcode
(Hex)
Addr Mode
dst src
opc
src
dst
3
26/10
94
RR
R
26/10
95
RR
IR
26/10
96
RR
IM
NOTE:
Execution takes 10 cycles if the divide-by-zero is attempted; otherwise it takes 26 cycles.
Examples:
Given: R0 = 10H, R1 = 03H, R2 = 40H, register 40H = 80H:
DIV RR0,R2
→
R0 = 03H, R1 = 40H
DIV RR0,@R2
→
R0 = 03H, R1 = 20H
DIV RR0,#20H
→
R0 = 03H, R1 = 80H
In the first example, destination working register pair RR0 contains the values 10H (R0) and 03H
(R1), and register R2 contains the value 40H. The statement "DIV RR0,R2" divides the 16-bit RR0
value by the 8-bit value of the R2 (source) register. After the DIV instruction, R0 contains the value
03H and R1 contains 40H. The 8-bit remainder is stored in the upper half of the destination register
RR0 (R0) and the quotient in the lower half (R1).