Table of Contents
Advertisement
EMAXM
MAX ((D), (M : M + 1)) ⇒ M : M + 1
Operation:
Description:
Subtracts an unsigned 16-bit value in memory from an unsigned 16-bit
value in double accumulator D to determine which is larger, and leaves
the larger of the two values in the memory location. The Z status bit is
set when the result of the subtraction is zero (the values are equal), and
the C status bit is set when the subtraction requires a borrow (the value
in memory is larger than the value in the accumulator). When C = 0, the
value in D has replaced the value in memory.
The unsigned value in memory is accessed by means of indexed ad-
dressing modes, which allow a great deal of flexibility in specifying the
address of the operand.
Condition Codes and Boolean Formulas:
S
–
N:
Z:
V:
C:
Condition codes reflect internal subtraction (R = D – M : M + 1).
Addressing Modes, Machine Code, and Execution Times:
Source Form
EMAXM oprx0_xysp
EMAXM oprx9,xysp
EMAXM oprx16,xysp
EMAXM [D ,xysp ]
EMAXM [ oprx16,xysp ]
MOTOROLA
6-82
Place Larger of Two
Unsigned 16-Bit Values
in Memory
X
H
I
N
Z
∆
∆
–
–
–
Set if MSB of result is set; cleared otherwise.
Set if result is $0000; cleared otherwise.
D15 • M15 • R15 + D15 • M15 • R15
Set if a two's complement overflow resulted from the operation;
cleared otherwise.
D15 • M15 + M15 • R15 + R15 • D15
Set if the value of the content of memory is larger than the value of
the accumulator; cleared otherwise.
Address Mode
IDX
IDX1
IDX2
[D,IDX]
[IDX2]
INSTRUCTION GLOSSARY
V
C
∆
∆
Object Code
18 1E xb
18 1E xb ff
18 1E xb ee ff
18 1E xb
18 1E xb ee ff
EMAXM
Cycles
Access Detail
4
ORPW
5
ORPWO
6
OfRPWP
7
OfIfRPW
7
OfIPRPW
CPU12
REFERENCE MANUAL
Advertisement
Table of Contents
