i386/i386.reference/PUSHF.htm

   1 <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
   2 <HTML>
   3 <HEAD>
   4 <TITLE>80386 Programmer's Reference Manual -- Opcode PUSHF</TITLE>
   5 </HEAD>
   6 <BODY>
   7 <B>up:</B> <A HREF="c17.htm">
   8 Chapter 17 -- 80386 Instruction Set</A><BR>
   9 <B>prev:</B><A HREF="PUSHA.htm"> PUSHA/PUSHAD Push all General Registers</A><BR>
  10 <B>next:</B><A HREF="RCL.htm"> RCL/RCR/ROL/ROR Rotate</A>
  11 <P>
  12 <HR>
  13 <P>
  14 <H1>PUSHF/PUSHFD -- Push Flags Register onto the Stack</H1>
  15
  16 <PRE>
  17 Opcode  Instruction  Clocks   Description
  18
  19 9C      PUSHF        4        Push FLAGS
  20 9C      PUSHFD       4        Push EFLAGS
  21 </PRE>
  22
  23
  24 <H2>Operation</H2>
  25
  26 <PRE>
  27 IF OperandSize = 32
  28 THEN push(EFLAGS);
  29 ELSE push(FLAGS);
  30 FI;
  31 </PRE>
  32
  33 <H2>Description</H2>
  34
  35 PUSHF decrements the stack pointer by 2 and copies the FLAGS
  36 register to the new top of stack; PUSHFD decrements the stack pointer by
  37 4, and the 80386 EFLAGS register is copied to the new top of stack
  38 which is pointed to by SS:eSP. Refer to
  39 <A HREF="c02.htm">Chapter 2</A> and
  40 <A HREF="c04.htm">Chapter 4</A> for
  41 information on the EFLAGS register.
  42
  43 <H2>Flags Affected</H2>
  44
  45 None
  46
  47 <H2>Protected Mode Exceptions</H2>
  48
  49 #SS(0) if the new value of eSP is outside the stack segment boundaries
  50
  51 <H2>Real Address Mode Exceptions</H2>
  52
  53 None; the 80386 shuts down due to a lack of stack space
  54
  55 <H2>Virtual 8086 Mode Exceptions</H2>
  56
  57 #GP(0) fault if IOPL is less than 3, to permit emulation
  58
  59
  60 <P>
  61 <HR>
  62 <P>
  63 <B>up:</B> <A HREF="c17.htm">
  64 Chapter 17 -- 80386 Instruction Set</A><BR>
  65 <B>prev:</B><A HREF="PUSHA.htm"> PUSHA/PUSHAD Push all General Registers</A><BR>
  66 <B>next:</B><A HREF="RCL.htm"> RCL/RCR/ROL/ROR Rotate</A>
  67 </BODY>