diff options
Diffstat (limited to 'bcopy32.inc')
| -rw-r--r-- | bcopy32.inc | 88 |
1 files changed, 23 insertions, 65 deletions
diff --git a/bcopy32.inc b/bcopy32.inc index 7b707801..5e3fda2b 100644 --- a/bcopy32.inc +++ b/bcopy32.inc @@ -27,11 +27,11 @@ ; segments, but this stuff is painful enough as it is without having to rely ; on everything happening "as it ought to." ; -; IMPORTANT: This code must be capable of operating when copied to the -; trackbuf area (1000h). The routine bcopy_over_self handles this mode -; of operation, including any necessary adjustments. +; NOTE: this code is relocated into low memory, just after the .earlybss +; segment, in order to support to "bcopy over self" operation. ; - section .text + + section .bcopy32 align 8 __bcopy_start: @@ -39,7 +39,7 @@ __bcopy_start: ; contiguous with the rest of the bcopy stuff bcopy_gdt: dw bcopy_gdt_size-1 ; Null descriptor - contains GDT -.adj1: dd bcopy_gdt ; pointer for LGDT instruction + dd bcopy_gdt ; pointer for LGDT instruction dw 0 dd 0000ffffh ; Code segment, use16, readable, dd 00009b00h ; present, dpl 0, cover 64K @@ -81,11 +81,11 @@ bcopy: push eax cli call enable_a20 -.adj2: o32 lgdt [cs:bcopy_gdt] + o32 lgdt [cs:bcopy_gdt] mov eax,cr0 or al,1 mov cr0,eax ; Enter protected mode -.adj3a: jmp 08h:.in_pm + jmp 08h:.in_pm .in_pm: mov ax,10h ; Data segment selector mov es,ax @@ -112,7 +112,7 @@ bcopy: push eax mov eax,cr0 and al,~1 mov cr0,eax ; Disable protected mode -.adj3b: jmp 0:.in_rm + jmp 0:.in_rm .in_rm: ; Back in real mode lss sp,[cs:SavedSSSP] @@ -145,11 +145,6 @@ bcopy: push eax %define A20_KBC 3 ; A20 through KBC %define A20_FAST 4 ; A20 through port 92h - align 2 -A20List dw a20_dunno, a20_none, a20_bios, a20_kbc, a20_fast -A20DList dw a20d_dunno, a20d_none, a20d_bios, a20d_kbc, a20d_fast -a20_adjust_cnt equ ($-A20List)/2 - slow_out: out dx, al ; Fall through _io_delay: out IO_DELAY_PORT,al @@ -173,7 +168,7 @@ try_enable_a20: ; mov bp,[cs:A20Type] add bp,bp ; Convert to word offset -.adj4: jmp word [cs:bp+A20List] + jmp word [cs:bp+A20List] ; ; First, see if we are on a system with no A20 gate @@ -299,7 +294,7 @@ disable_a20: mov bp,[cs:A20Type] add bp,bp ; Convert to word offset -.adj5: jmp word [cs:bp+A20DList] + jmp word [cs:bp+A20DList] a20d_bios: mov ax,2400h @@ -396,52 +391,7 @@ try_wbinvd: ; ESI, EDI, ECX - same as bcopy ; On stack - initial state (fd, ad, ds, es, fs, gs) ; -ADJUST equ (__bcopy_start - $$) + TEXT_START - BSS_START - - align 2 -adjlist dw bcopy_gdt.adj1 - ADJUST - dw bcopy.adj2 + 5 - ADJUST - dw bcopy.adj3a + 1 - ADJUST - dw bcopy.adj3b + 1 - ADJUST - dw try_enable_a20.adj4 + 3 - ADJUST - dw disable_a20.adj5 + 3 - ADJUST -adjlist_cnt equ ($-adjlist)/2 - bcopy_over_self: - push esi - push edi - push ecx - - xor bx,bx - mov es,bx - mov ds,bx - - mov si,__bcopy_start - mov di,trackbuf ; == BSS_START - mov cx,(__bcopy_end - __bcopy_start + 3) >> 2 - rep movsd - - mov si,A20List - ADJUST - mov cx,a20_adjust_cnt -.adjust1: - sub word [si], ADJUST - inc si - inc si - loop .adjust1 - - mov si, adjlist - mov cx, adjlist_cnt -.adjust2: - lodsw - xchg di,ax - sub word [di], ADJUST - loop .adjust2 - - jmp .next-ADJUST -.next: - pop ecx - pop edi - pop esi call bcopy pop gs @@ -451,9 +401,17 @@ bcopy_over_self: popad popfd jmp 0:7c00h -__bcopy_end: - section .earlybss -A20Test resw 1 ; Counter for testing status of A20 -A20Type resw 1 ; A20 type -A20Tries resb 1 ; Times until giving up on A20 + align 2 +A20List dw a20_dunno, a20_none, a20_bios, a20_kbc, a20_fast +A20DList dw a20d_dunno, a20d_none, a20d_bios, a20d_kbc, a20d_fast +a20_adjust_cnt equ ($-A20List)/2 + +A20Type dw A20_NONE ; A20 type +A20Test dw 0 ; Counter for testing status of A20 +A20Tries db 0 ; Times until giving up on A20 + + ; Total size of .bcopy32 section + alignb 4, db 0 ; Even number of dwords +__bcopy_size equ $-__bcopy_start + |