Texas Instruments TMS320C28x Reference Manual page 390

MPYA P,T,loc16
SYNTAX OPTIONS
MPYA P,T,loc16
Operands P
T
loc16
Description
Flags and Z
Modes
N
C
V
OVC
OVM
PM
Repeat
0001 0111 LLLL LLLL
Product register
Multiplicand register
Addressing mode (see Chapter 5)
Add the previous product (stored in the P register), shifted as specified by the
product shift mode (PM), to the ACC register. Multiply the signed 16-bit
content of T by the signed 16-bit content of the location pointed to by the
"loc16" addressing mode and store the 32-bit result in the P register:
ACC = ACC + P << PM;
P = signed T * signed [loc16];
After the operation, the Z flag is set if the ACC is zero, else Z is cleared.
After the addition, the N flag is set if bit 31 of the ACC is 1, else N is cleared.
If the addition generates a carry, C is set; otherwise C is cleared.
If an overflow occurs, V is set; otherwise V is not affected.
If overflow mode is disabled; and if the operation generates a positive
overflow, then the counter is incremented. If overflow mode is disabled; and if
the operation generates a negative overflow, then the counter is
decremented.
If overflow mode bit is set; then the ACC value will saturate maximum
positive (0x7FFFFFFF) or maximum negative (0x80000000) if the operation
overflowed.
The value in the PM bits sets the shift mode for the output operation from the
product register. If the product shift value is positive (logical left shift
operation), then the low bits are zero filled. If the product shift value is
negative (arithmetic right shift operation), the upper bits are sign extended.
This instruction is repeatable. If the operation follows a RPT instruction, then
it will be executed N+1 times. The state of the Z, N, C and OVC flags will
reflect the final result. The V flag will be set if an intermediate overflow
occurs.
16 X 16-bit Multiply and Add Previous Product
OPCODE OBJMODE
MPYA P,T,loc16
RPT CYC
X Y N+1
6-233