Slide 7.6: Flags affected by addition and subtraction (cont.)

Slide 7.5: Flags affected by addition and subtraction
Slide 7.7: Flags affected by addition and subtraction (cont.)
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Flags Affected by Addition and Subtraction (Cont.)

`0FFh + 1`	`00h – 1`	`00h – 1`
INCLUDE Irvine32.inc .data X SWORD 12FFh .code main PROC movsx ebx, X inc bl call DumpRegs jz L1 call WaitMsg L1: mov X, bx movsx eax, X call WriteHex exit main ENDP END main	INCLUDE Irvine32.inc .data X SWORD 0FF00h .code main PROC movsx ebx, X dec bl call DumpRegs mov X, bx js L1 call WaitMsg L1: movsx eax, X call WriteHex exit main ENDP END main	INCLUDE Irvine32.inc .data X SWORD 0FF00h .code main PROC movsx ebx, X sub bl, 1 call DumpRegs mov X, bx js L1 call WaitMsg L1: movsx eax, X call WriteHex exit main ENDP END main
Output	Output	Output
CF= SF= ZF= OF= AF= PF= EAX=	CF= SF= ZF= OF= AF= PF= EAX =	CF= SF= ZF= OF= AF= PF= EAX=

The and instructions do not affect the Carry flag.
The instruction performs the addition based on the size of the first argument. The procedure , provided by the textbook author, displays the message “Press [Enter] to continue ....,” and waits for the user to press the key.

`[X + 1] + 1`	`0FF0Fh + 1`	`0101h + 1`
INCLUDE Irvine32.inc .data X SWORD 0FF00h .code main PROC add X+1, 1 call DumpRegs jz L1 call WaitMsg L1: movsx eax, X call WriteHex exit main ENDP END main	INCLUDE Irvine32.inc .data Dummy WORD ? .code main PROC mov bx, 0FF0Fh add bl, 1 call DumpRegs lahf test ah, 00010000b jz L1 call WaitMsg L1: movsx eax, bx call WriteHex exit main ENDP END main	INCLUDE Irvine32.inc .data Dummy WORD ? .code main PROC mov bx, 0101h add bx, 1 call DumpRegs jp L1 call WaitMsg L1: movsx eax, bx call WriteHex exit main ENDP END main
Output	Output	Output
CF= SF= ZF= OF= AF= PF= EAX=	CF= SF= ZF= OF= AF= PF= EAX=	CF= SF= ZF= OF= AF= PF= EAX=

“I’m not arguing, I’m just explaining why I’m right.”
― Unknown