INSTRUCTION SET S3F80P5_UM_ REV1.00
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 ≥ 28, 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 28 and 29 –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 ≥ 28 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).
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