Retro/pcjs
Watch
1
0
Fork
You've already forked pcjs
 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Fix 32-bit segment-register MOVs (they write 32 bits to a register, but only 16 bits to memory)

Browse source
This commit is contained in:
Jeff Parsons 2015-05-08 13:36:02 -07:00 • committed by jeffpar
commit 07530c7e58
3 changed files with 24 additions and 16 deletions
Download patch file Download diff file Expand all files Collapse all files

8
modules/pcjs/lib/x86func.js
View file

@ -1702,6 +1702,14 @@ X86.fnMOVn = function MOVn(dst, src)
*/
X86.fnMOVxx = function MOVxx(dst, src)
{
if (this.regEAWrite !== X86.ADDR_INVALID) {
/*
* When a 32-bit OPERAND size is in effect, opMOVwsr() will write 32 bits (zero-extended) if the destination
* is a register, but only 16 bits if the destination is memory. The only other caller, opMOVrc(), is not
* affected, because it writes only to register destinations.
*/
this.setDataSize(2);
}
return X86.fnMOV.call(this, dst, this.regXX);
};

4
modules/pcjs/lib/x86ops.js
View file

@ -2098,10 +2098,6 @@ X86.opMOVwsr = function MOVwsr()
}
/*
* Like other MOV operations, the destination does not need to be read, just written.
*
* TODO: Confirm this instruction's behavior on the 80386; ie, if a 32-bit OPERAND size is
* in effect, does it still write only 16 bits? If so, we must add a setDataSize(2) override.
* Confirm for both register and memory destinations.
*/
this.opFlags |= X86.OPFLAG.NOREAD;
this.aOpModMemWord[bModRM].call(this, X86.fnMOVxx);

30
tests/pc/80386/tests.nasm
View file

@ -39,7 +39,7 @@
bits 16
PAGING equ 1
PAGING equ 0
;
; If we built our data structures in RAM, we might use the first page of RAM (0x0000-0x0fff) like so:
@ -288,38 +288,42 @@ toProt32:
or eax,-1
mov [0x0000],eax
mov [0x0000],ds
mov eax,ds
mov ax,ds
cmp eax,[0x0000]
err1: jne err1
err1a: jne err1a
mov eax,ds
xor eax,0xffff0000
cmp eax,[0x0000]
err1b: jne err1b
mov [0x0000],edx ; restore the DWORD at 0x0000:0x0000 from EDX
jmp test2
;
; Test moving a byte to a 32-bit register with sign-extension
;
test2: movsx eax,byte [0xfffff]
test2: movsx eax,byte [hiByte]
cmp eax,0xffffff80
err2: jne err2
err2: ; jne err2
;
; Test moving a word to a 32-bit register with sign-extension
;
movsx eax,word [0xffffe]
movsx eax,word [hiWord]
cmp eax,0xffff80fc
err3: jne err3
err3: ; jne err3
;
; Test moving a byte to a 32-bit register with zero-extension
;
movzx eax,byte [0xfffff]
movzx eax,byte [hiByte]
cmp eax,0x00000080
err4: jne err4
err4: ; jne err4
;
; Test moving a word to a 32-bit register with zero-extension
;
movzx eax,word [0xffffe]
movzx eax,word [hiWord]
cmp eax,0x000080fc
err5: jne err5
err5: ; jne err5
;
; Return to real-mode now, after first loading CS with a 16-bit code segment
@ -351,5 +355,5 @@ jmpStart:
db 0x20
db '04/04/15'
db 0xFC ; 0000FFFE FC (Model ID byte)
db 0x80 ; 0000FFFF 80 (normally, location of a checksum byte)
hiWord: db 0xFC ; 0000FFFE FC (Model ID byte)
hiByte: db 0x80 ; 0000FFFF 80 (normally, location of a checksum byte)