diff options
Diffstat (limited to 'core/bcopy32.inc')
| -rw-r--r-- | core/bcopy32.inc | 77 |
1 files changed, 28 insertions, 49 deletions
diff --git a/core/bcopy32.inc b/core/bcopy32.inc index f058a6f7..c7155574 100644 --- a/core/bcopy32.inc +++ b/core/bcopy32.inc @@ -127,7 +127,7 @@ simple_pm_call: bits 32 .in_pm: - mov eax,PM_DS32 + mov ax,PM_DS32 mov ss,eax lea esp,[ebp-8*4-2*4] ; Flat mode stack mov es,eax @@ -137,7 +137,7 @@ simple_pm_call: ; machine running on Intel VT hardware -- it can't ; deal with a partial transition, for no good reason. - mov al,PM_DS16_RM ; Real-mode-like segment + mov al,PM_DS16 ; Real-mode-like segment mov fs,eax mov gs,eax mov al,PM_TSS ; Intel VT really doesn't want @@ -151,7 +151,7 @@ simple_pm_call: jmp PM_CS16:.exit bits 16 .exit: - mov eax,PM_DS16_RM ; "Real-mode-like" data segment + mov ax,PM_DS16 ; "Real-mode-like" data segment mov es,eax mov ds,eax mov ss,eax @@ -189,29 +189,22 @@ simple_pm_call: ; ; We typically toggle A20 twice for every 64K transferred. ; -%define io_delay call _io_delay %define IO_DELAY_PORT 80h ; Invalid port (we hope!) -%define disable_wait 32 ; How long to wait for a disable - -; Note the skip of 2 here -%define A20_DUNNO 0 ; A20 type unknown -%define A20_NONE 2 ; A20 always on? -%define A20_BIOS 4 ; A20 BIOS enable -%define A20_KBC 6 ; A20 through KBC -%define A20_FAST 8 ; A20 through port 92h slow_out: out dx, al ; Fall through -_io_delay: out IO_DELAY_PORT,al +%macro io_delay 0 out IO_DELAY_PORT,al - ret + out IO_DELAY_PORT,al +%endmacro section .data - align 2 + alignz 2 A20Ptr dw a20_dunno section .bss -A20Test resw 1 ; Counter for testing A20 status + alignb 4 +A20Test resd 1 ; Counter for testing A20 status A20Tries resb 1 ; Times until giving up on A20 section .text @@ -220,30 +213,21 @@ enable_a20: mov byte [cs:A20Tries],255 ; Times to try to make this work try_enable_a20: -; -; Flush the caches -; -%if DO_WBINVD - call try_wbinvd -%endif - -; -; If the A20 type is known, jump straight to type -; - jmp word [cs:A20Ptr] ; -; First, see if we are on a system with no A20 gate +; First, see if we are on a system with no A20 gate, or the A20 gate +; is already enabled for us... ; -a20_dunno: a20_none: - mov word [cs:A20Ptr], a20_none call a20_test jnz a20_done + ; Otherwise, see if we had something memorized... + jmp word [cs:A20Ptr] ; ; Next, try the BIOS (INT 15h AX=2401h) ; +a20_dunno: a20_bios: mov word [cs:A20Ptr], a20_bios mov ax,2401h @@ -337,20 +321,24 @@ a20_done: popad ; This routine tests if A20 is enabled (ZF = 0). This routine ; must not destroy any register contents. ; +; The no-write early out avoids the io_delay in the (presumably common) +; case of A20 already enabled (e.g. from a previous call.) +; a20_test: push es push cx - push ax - mov cx,0FFFFh ; HMA = segment 0FFFFh + push eax + mov cx,0FFFFh ; HMA = segment 0FFFFh mov es,cx - mov cx,32 ; Loop count - mov ax,[cs:A20Test] -.a20_wait: inc ax - mov [cs:A20Test],ax - io_delay ; Serialize, and fix delay - cmp ax,[es:A20Test+10h] - loopz .a20_wait -.a20_done: pop ax + mov eax,[cs:A20Test] + mov cx,32 ; Loop count + jmp .test ; First iteration = early out +.wait: add eax,0x430aea41 ; A large prime number + mov [cs:A20Test],eax + io_delay ; Serialize, and fix delay +.test: cmp eax,[es:A20Test+10h] + loopz .wait +.done: pop eax pop cx pop es ret @@ -381,15 +369,6 @@ empty_8042: .done: ret ; -; Execute a WBINVD instruction if possible on this CPU -; -%if DO_WBINVD -try_wbinvd: - wbinvd - ret -%endif - -; ; The 32-bit copy and shuffle code is "special", so it is in its own file ; %include "bcopyxx.inc" |