Texas Instruments TMS320C28x Reference Manual page 474

SBBU ACC,loc16
SYNTAX OPTIONS
SBBU ACC,loc16
Operands ACC
loc16
Description
Flags and Z
Modes
N
C
V
OVC
OVM
Repeat
Example
; Subtract three 32-bit unsigned variables by 16-bit parts:
MOVU
ADD
SUBU
SUB
SBBU
SUB
Accumulator register
Addressing mode (see Chapter 5)
Subtract the 16-bit contents of the location pointed to by the "loc16"
addressing mode, zero extended, and subtract the compliment of the carry
flag bit from the ACC register:
ACC = ACC − 0:[loc16] − ~C;
After the subtraction, the Z flag is set if ACC is zero, else Z is cleared.
After the subtraction, the N flag is set if bit 31 of the ACC is 1, else N is
cleared.
The state of the carry bit before execution is included in the subtraction. If the
subtraction generates a borrow, C is cleared; otherwise C is set.
If an overflow occurs, V is set; otherwise V is not affected.
If(OVM = 0, disabled) then if the operation generates a positive overflow,
then the counter is incremented and if the operation generates a negative
overflow, then the counter is decremented. If(OVM = 1, enabled) then the
counter is not affected by the operation.
If overflow mode bit is set; then the ACC value will saturate maximum
positive (0x7FFFFFFF) or maximum negative (0x80000000) if the operation
overflowed.
This instruction is not repeatable. If this instruction follows the RPT
instruction, it resets the repeat counter (RPTC) and executes only once.
ACC,@VarAlow
ACC,@VarAhigh << 16
ACC,@VarBlow
ACC,@VarBhigh << 16
ACC,@VarClow
ACC,@VarChigh << 16
Subtract Unsigned Value Plus Inverse Borrow
OPCODE
0001 1101 LLLL LLLL
; AH = 0, AL = VarAlow
; AH = VarAhigh, AL = VarAlow
; ACC = ACC − 0:VarBlow
; ACC = ACC − VarBhigh << 16
; ACC = ACC − VarClow − ~Carry
; ACC = ACC − VarChigh << 16
SBBU ACC,loc16
OBJMODE RPT CYC
X − 1
6-317