i386/i386.reference/PUSHA.htm

   1 <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
   2 <HTML>
   3 <HEAD>
   4 <TITLE>80386 Programmer's Reference Manual -- Opcode PUSHA</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="PUSH.htm"> PUSH Push Operand onto the Stack</A><BR>
  10 <B>next:</B><A HREF="PUSHF.htm"> PUSHF/PUSHFD Push Flags Register onto the Stack</A>
  11 <P>
  12 <HR>
  13 <P>
  14 <H1>PUSHA/PUSHAD -- Push all General Registers</H1>
  15
  16 <PRE>
  17 Opcode  Instruction  Clocks   Description
  18
  19 60      PUSHA        18       Push AX, CX, DX, BX, original SP, BP, SI, and
  20                               DI
  21 60      PUSHAD       18       Push EAX, ECX, EDX, EBX, original ESP, EBP,
  22                               ESI, and EDI
  23 </PRE>
  24
  25
  26 <H2>Operation</H2>
  27
  28 <PRE>
  29 IF OperandSize = 16 (* PUSHA instruction *)
  30 THEN
  31    Temp := (SP);
  32    Push(AX);
  33    Push(CX);
  34    Push(DX);
  35    Push(BX);
  36    Push(Temp);
  37    Push(BP);
  38    Push(SI);
  39    Push(DI);
  40 ELSE (* OperandSize = 32, PUSHAD instruction *)
  41    Temp := (ESP);
  42    Push(EAX);
  43    Push(ECX);
  44    Push(EDX);
  45    Push(EBX);
  46    Push(Temp);
  47    Push(EBP);
  48    Push(ESI);
  49    Push(EDI);
  50 FI;
  51 </PRE>
  52
  53 <H2>Description</H2>
  54
  55 PUSHA and PUSHAD save the 16-bit or 32-bit general registers,
  56 respectively, on the 80386 stack. PUSHA decrements the stack pointer
  57 (SP) by 16 to hold the eight word values. PUSHAD decrements the
  58 stack pointer (ESP) by 32 to hold the eight doubleword values. Because
  59 the registers are pushed onto the stack in the order in which they were
  60 given, they appear in the 16 or 32 new stack bytes in reverse order. The
  61 last register pushed is DI or EDI.
  62
  63 <H2>Flags Affected</H2>
  64
  65 None
  66
  67 <H2>Protected Mode Exceptions</H2>
  68
  69 #SS(0) if the starting or ending stack address is outside the stack segment
  70 limit; #PF(fault-code) for a page fault
  71
  72 <H2>Real Address Mode Exceptions</H2>
  73
  74 Before executing PUSHA or PUSHAD, the 80386 shuts down if SP or
  75 ESP equals 1, 3, or 5; if SP or ESP equals 7, 9, 11, 13, or 15, exception
  76 13 occurs
  77
  78 <H2>Virtual 8086 Mode Exceptions</H2>
  79
  80 Same exceptions as in real-address mode; #PF(fault-code) for a page
  81 fault
  82
  83
  84 <P>
  85 <HR>
  86 <P>
  87 <B>up:</B> <A HREF="c17.htm">
  88 Chapter 17 -- 80386 Instruction Set</A><BR>
  89 <B>prev:</B><A HREF="PUSH.htm"> PUSH Push Operand onto the Stack</A><BR>
  90 <B>next:</B><A HREF="PUSHF.htm"> PUSHF/PUSHFD Push Flags Register onto the Stack</A>
  91 </BODY>