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ARM INSTRUCTION SET S3C2440A RISC MICROPROCESSOR
3-24
CPSR FLAGS
Setting the CPSR flags is optional, and is controlled by the S bit in the instruction. The N (Negative) and Z (Zero)
flags are set correctly on the result (N is made equal to bit 31 of the result, and Z is set if and only if the result is
zero). The C (Carry) flag is set to a meaningless value and the V (oVerflow) flag is unaffected.
INSTRUCTION CYCLE TIMES
MUL takes 1S + mI and MLA 1S + (m+1)I cycles to execute, where S and I are defined as sequential (S-cycle) and
internal (I-cycle), respectively.
m The number of 8 bit multiplier array cycles is required to complete the multiply, which is
controlled by the value of the multiplier operand specified by Rs. Its possible values are
as follows
1 If bits [32:8] of the multiplier operand are all zero or all one.
2 If bits [32:16] of the multiplier operand are all zero or all one.
3 If bits [32:24] of the multiplier operand are all zero or all one.
4 In all other cases.
ASSEMBLER SYNTAX
MUL{cond}{S} Rd,Rm,Rs
MLA{cond}{S} Rd,Rm,Rs,Rn
{cond} Two-character condition mnemonic. See Table 3-2..
{S} Set condition codes if S present
Rd, Rm, Rs and Rn Expressions evaluating to a register number other than R15.
EXAMPLES
MUL R1,R2,R3 ; R1:=R2*R3
MLAEQS R1,R2,R3,R4 ; Conditionally R1:=R2*R3+R4, Setting condition codes.