MAC
SC140 DSP Core Reference Manual
A-233
MAC
Signed Fractional Multiply-Accumulate (DALU)
MAC
Description
These operations perform signed fractional multiplication of two 16-bit signed operands (Da.H and Db.H).
They then add or subtract the product to or from a data register (Dn). One operand is the HP of a data
register. The other operand is either the HP of a data register or an immediate 16-bit signed data.
Status and Conditions that Affect Instruction
Status and Conditions Changed by Instruction
Example 1
mac d4,d5,d6
Operation
Assembler Syntax
Dn + (#s16 * Da.H)
→
Dn
MAC #s16,Da,Dn {–2
15
≤
s16
<
2
15
}
Dn
±
(Da.H * Db.H)
→
Dn
MAC
±
Da,Db,Dn
MAC #s16,Da,Dn
Adds the product of an immediate 16-bit word and a data register (Da) to the destination register (Dn).
MAC
±
Da,Db,Dn
Multiplies the HP contents of two data registers (Da, Db) and adds or subtracts the product to or from a
destination data register (Dn). The default is to add the product to the destination register.
Register Address
Bit Name
Description
SR[2]
SM
If set, selects 32-bit arithmetic saturation mode.
SR[5:4]
S[1:0]
Scaling mode bits determine which bits in the result are used in the
Ln bit calculation.
Register Address
Bit Name
Description
Ln
L
If not in arithmetic saturation mode (SR [SM] = 0), calculates and
updates the Ln bit in the destination register. If in arithmetic
saturation mode (SR [SM] = 1), clears the Ln bit in the destination
register.
EMR[2]
DOVF
Set if the result cannot be represented in 40 bits, or if the result
saturates to 32 bits in arithmetic saturation mode.
Register/Memory Address
Before
After
SR
$00E0 0000
D4
$00 1000 0000
Summary of Contents for SC140 DSP Core
Page 12: ...xii SC140 DSP Core Reference Manual ...
Page 18: ...xviii SC140 DSP Core Reference Manual ...
Page 32: ...1 6 SC140 DSP Core Reference Manual Core Architecture Features ...
Page 180: ...4 70 SC140 DSP Core Reference Manual Trace Unit Registers ...
Page 250: ...6 70 SC140 DSP Core Reference Manual Programming Rules ...
Page 314: ...7 64 SC140 DSP Core Reference Manual NOP Definition ...
Page 463: ...DI SC140 DSP Core Reference Manual A 149 15 8 7 0 DI 1 1 4 1 0 0 1 1 1 1 1 0 1 1 1 1 1 0 1 ...
Page 478: ...A 164 SC140 DSP Core Reference Manual EI ...
Page 618: ...A 304 SC140 DSP Core Reference Manual MOVES 4F s15 sssssssssssssss Signed 15 bit offset ...
Page 638: ...A 324 SC140 DSP Core Reference Manual MPYR ...
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Page 758: ...I 10 Index ...
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