- The carry and overflow flags are set relative to the data size used in the addition
- adc source, destination
- movl data+4, %ebx
- printf("%qd")
pushl 高位
pushl 低位
有符号数的加减是否影响 CF?
- NEG
NEG命令无论你是否为正负数，都会按照取反+1或用0减去这个数的二进制的办法去计算
The carry flag was set when the result was less than zero
SBB instruction utilizes the carry and overflow flags in multibyte subtractions to implement the borrow feature across data boundaries
increment (INC) and decrement (DEC) an unsigned integer
mul source
two unsigned integers
AL, AX, or EAX
DX:AX
EDX:EAX
- using indexed memory access
IMUL instruction can be used by both signed and unsigned integers,
although you must be careful that the result does not use the most significant bit of the destination. For larger values,
the IMUL instruction is only valid for signed integers
- imul source
- imul source, destination
source can be a 16- or 32-bit register or value in memory, and destination must be a 16- or 32-bit general-purpose register
- imul multiplier, source, destination
where multiplier is an immediate value, source is a 16- or 32-bit register or value in memory, and destination must be a general-purpose register
- div
dividend in AX, DX:AX, EDX:EAX
低位存储商
- idiv
only one format for the IDIV instruction
For signed integer division, the sign of the remainder is always the sign of the dividend
SAL (shift arithmetic left)
SHL (shift logical left)
sal destination
sal %cl, destination
sal shifter, destination
- destination operand can be an 8-, 16-, or 32-bit register or value in memory
- Any bits that are shifted out of the data size are first placed in the carry
flag, and then dropped in the next shift
- SHR
- SAR
first moved to the carry flag, and then
shifted out
ROL
ROR
RCL
RCR
AAA
AAS
AAM
AAD
only AAD 用在 DIV 之前
都使用默认的 AL register
- Packed BCD arithmetic
- DAA: Adjusts the result of the ADD or ADC instructions
- DAS: Adjusts the result of the SUB or SBB instructions
