Add, Adc, Sub, Sbc, And Rsb - ST STM32F4 Series Programming Manual

The STM32 Cortex-M4 instruction set
3.5.1

ADD, ADC, SUB, SBC, and RSB

Add, Add with Carry, Subtract, Subtract with Carry, and Reverse Subtract.
Syntax
op{S}{cond} {Rd,} Rn, Operand2
op{cond} {Rd,} Rn, #imm12; ADD and SUB only
Where:
•
'op' is one of the following:
ADD: Add
ADC: Add with carry
SUB: Subtract
SBC: Subtract with carry
RSB: Reverse subtract
•
'S' is an optional suffix. If S is specified, the condition code flags are updated on the
result of the operation (see
• 'cond' is an optional condition code (see
•
'Rd' is the destination register. If Rd is omitted, the destination register is Rn
•
'Rn' is the register holding the first operand
•
'Operand2' is a flexible second operand (see
details of the options)
•
'imm12' is any value in the range 0—4095
Operation
The ADD instruction adds the value of operand2 or imm12 to the value in Rn.
The ADC instruction adds the values in Rn and operand2, together with the carry flag.
The SUB instruction subtracts the value of operand2 or imm12 from the value in Rn.
The SBC instruction subtracts the value of operand2 from the value in Rn. If the carry flag is
clear, the result is reduced by one.
The RSB instruction subtracts the value in Rn from the value of operand2. This is useful
because of the wide range of options for operand2.
Use ADC and SBC to synthesize multiword arithmetic (see
on page 83
ADDW is equivalent to the ADD syntax that uses the imm12 operand. SUBW is equivalent
to the SUB syntax that uses the imm12 operand.
82/260
Conditional execution on page
and ADR on page 69).
DocID022708 Rev 6
64)
Conditional execution on page
Flexible second operand on page 59
Multiword arithmetic examples
PM0214
64)
for