Add Scheme_Stack_Segment_Selector for DOS, and make sure that esp is

loaded immediately after ss because the 386 architecture masks
interrupts for one instruction after modifying ss.

diff --git a/v7/src/microcode/cmpauxmd/i386.m4 b/v7/src/microcode/cmpauxmd/i386.m4
index c352ff184e952d2b3f6657c425c862f3f41dcff2..0cb2df920744e5f21f3d71e43acfcb40568d2419 100644 (file)
--- a/v7/src/microcode/cmpauxmd/i386.m4
+++ b/v7/src/microcode/cmpauxmd/i386.m4
@@ -1,6 +1,6 @@
 ### -*-Midas-*-
 ###
-###    $Header: /Users/cph/tmp/foo/mit-scheme/mit-scheme/v7/src/microcode/cmpauxmd/i386.m4,v 1.26 1992/08/24 15:21:27 jinx Exp $
+###    $Id: i386.m4,v 1.27 1992/09/18 02:05:26 jinx Exp $
 ###
 ###    Copyright (c) 1992 Massachusetts Institute of Technology
 ###
@@ -292,8 +292,10 @@ use_external_data(Free)
 use_external_data(Ext_Stack_Pointer)
 use_external_data(utility_table)
 
-IFDOS(`define_data(C_Stack_Segment)
-allocate_longword(C_Stack_Segment)')
+IFDOS(`define_data(C_Stack_Segment_Selector)
+allocate_longword(C_Stack_Segment_Selector)
+define_data(Scheme_Stack_Segment_Selector)
+allocate_longword(Scheme_Stack_Segment_Selector)')
 
 define_data(C_Stack_Pointer)
 allocate_longword(C_Stack_Pointer)
@@ -317,6 +319,15 @@ declare_alignment(2)
 define_c_label(i386_interface_initialize)
        OP(push,l)      REG(ebp)
        OP(mov,l)       TW(REG(esp),REG(ebp))
+
+                                                       # Initialize stack
+                                                       # selectors
+IFDOS(`        OP(xor,l)       TW(REG(eax),REG(eax))
+       OP(mov,w)       TW(REG(ss),REG(ax))
+       OP(mov,l)       TW(REG(eax),EDR(C_Stack_Segment_Selector))
+       OP(mov,w)       TW(REG(ds),REG(ax))
+       OP(mov,l)       TW(REG(eax),EDR(Scheme_Stack_Segment_Selector))')
+
        OP(xor,l)       TW(REG(eax),REG(eax))           # No 387 available
 
 # Unfortunately, the `movl cr0,ecx' instruction is privileged.
@@ -361,10 +372,6 @@ define_c_label(C_to_interface)
        OP(mov,l)       TW(REG(esp),EDR(C_Stack_Pointer))
                                                        # Register block = %esi
 
-IFDOS(`        OP(mov,w)       TW(REG(ss),REG(ax))             # Obtain stack segment
-                                                       # and preserve it
-       OP(mov,l)       TW(REG(eax),EDR(C_Stack_Segment))')
-
        OP(lea,l)       TW(ABS(EDR(Registers)),regs)
        jmp     external_code_reference(interface_to_scheme)
 
@@ -384,8 +391,7 @@ define_debugging_label(scheme_to_interface)
        OP(mov,l)       TW(REG(esp),EDR(Ext_Stack_Pointer))
        OP(mov,l)       TW(rfree,EDR(Free))
 
-IFDOS(`        OP(mov,l)       TW(EDR(C_Stack_Segment),REG(edi)) # Swap stack segments
-       OP(mov,w)       TW(REG(di),REG(ss))')
+IFDOS(`        OP(mov,w)       TW(EDR(C_Stack_Segment_Selector),REG(ss))')     # Swap stack segments
 
        OP(mov,l)       TW(EDR(C_Stack_Pointer),REG(esp))
        OP(mov,l)       TW(EDR(C_Frame_Pointer),REG(ebp))
@@ -411,11 +417,11 @@ define_c_label(interface_to_scheme)
                                                        # Value/dynamic link
        OP(mov,l)       TW(LOF(REGBLOCK_VAL(),regs),REG(eax))
        OP(mov,l)       TW(IMM(ADDRESS_MASK),rmask)     # = %ebp
-       OP(mov,l)       TW(EDR(Ext_Stack_Pointer),REG(esp))
 
-IFDOS(`        OP(mov,w)       TW(REG(ds),REG(bx))             # Swap stack segments
-       OP(mov,w)       TW(REG(bx),REG(ss))')
+                                                       # Swap stack segments
+IFDOS(`        OP(mov,w)       TW(EDR(Scheme_Stack_Segment_Selector),REG(ss))')
 
+       OP(mov,l)       TW(EDR(Ext_Stack_Pointer),REG(esp))
        OP(mov,l)       TW(REG(eax),REG(ecx))           # Preserve if used
        OP(and,l)       TW(rmask,REG(ecx))              # Restore potential
                                                        #  dynamic link