Chapter 3. Hardware Multiply/Accumulate (MAC) Unit
3-5
MAC Instruction Execution Timings
3.1.4 Data Representation
The MAC unit supports three basic operand types:
•
Two’s complement signed integer: In this format, an N-bit operand represents a
number within the range -2
(N-1)
< operand < 2
(N-1)
- 1. The binary point is to the right
of the least significant bit.
•
Two’s complement unsigned integer: In this format, an N-bit operand represents a
number within the range 0 < operand < 2
N
- 1. The binary point is to the right of the
least significant bit.
•
Two’s complement, signed fractional: In an N-bit number, the first bit is the sign bit.
The remaining bits signify the first N-1 bits after the binary point. Given an N-bit
number, a
N-1
a
N-2
a
N-3
... a
2
a
1
a
0
, its value is given by the following formula:
This format can represent numbers in the range -1 < operand < 1 - 2
(N-1)
.
For words and longwords, the greatest negative number that can be represented is -1,
whose internal representation is 0x8000 and 0x0x8000_0000, respectively. The
most positive word is 0x7FFF or (1 - 2
-15
); the most positive longword is
0x7FFF_FFFF or (1 - 2
-31
).
3.2 MAC Instruction
Execution Timings
For information on MAC instruction execution timings, refer to Section 2.7, “Instruction
Timing.”
2
i
1
N
–
+
(
)
ai
⋅
i
0
=
N
2
–
∑
+
Содержание DigitalDNA ColdFire MCF5272
Страница 1: ...MCF5272UM D Rev 0 02 2001 MCF5272 ColdFire Integrated Microprocessor User s Manual ...
Страница 38: ...xxxviii MCF5272 User s Manual TABLES Table Number Title Page Number ...
Страница 58: ...1 10 MCF5272 User s Manual MCF5272 Specific Features ...
Страница 90: ...2 42 MCF5272 User s Manual Exception Processing Overview ...
Страница 96: ...3 6 MCF5272 User s Manual MAC Instruction Execution Timings ...
Страница 158: ...5 46 MCF5272 User s Manual Motorola Recommended BDM Pinout ...
Страница 184: ...7 12 MCF5272 User s Manual Interrupt Controller Registers ...
Страница 338: ...13 44 MCF5272 User s Manual Application Examples ...
Страница 414: ...18 6 MCF5272 User s Manual PWM Programming Model ...
Страница 452: ...19 38 MCF5272 User s Manual Power Supply Pins ...
Страница 482: ...20 30 MCF5272 User s Manual Reset Operation ...
Страница 492: ...21 10 MCF5272 User s Manual Non IEEE 1149 1 Operation ...
Страница 548: ...INDEX Index 12 MCF5272 User s Manual ...