EDD code, not enabled by default

diff --git a/memdisk/memdisk.asm b/memdisk/memdisk.asm
index c59704d..e40be84 100644 (file)
--- a/memdisk/memdisk.asm
+++ b/memdisk/memdisk.asm
@@ -23,6 +23,12 @@
 
 ; %define DEBUG_TRACERS                        ; Uncomment to get debugging tracers
 
+%ifdef WITH_EDD
+%define EDD 1
+%else
+%define EDD 0
+%endif
+
 %ifdef DEBUG_TRACERS
 
 %macro TRACER  1
@@ -318,8 +324,64 @@ GetParms:
 .notic:
                xor ax,ax
                ret
-               
-               ; Set up registers as for a "Read", and compares against disk size
+;
+; EDD functions -- only if enabled
+;
+%if EDD
+EDDPresence:
+               cmp P_BX,55AAh
+               jne Invalid
+               mov P_BX,0AA55h         ; EDD signature
+               mov P_AX,03000h         ; EDD 3.0
+               mov P_CX,0001h          ; Fixed disk access subset
+               pop ax                  ; Drop return address
+               xor ax,ax               ; Success
+               jmp DoneWeird           ; Success, but AH != 0, sigh...
+
+EDDRead:
+               call edd_setup_regs
+               call bcopy
+               xor ax,ax
+               ret
+
+EDDWrite:
+               call edd_setup_regs
+               xchg esi,edi
+               call bcopy
+               xor ax,ax
+               ret
+
+EDDVerify:
+EDDSeek:
+               call edd_setup_regs     ; Just bounds checking
+               xor ax,ax
+               ret
+
+EDDGetParms:
+               mov es,P_DS
+               mov di,P_SI
+               mov cx,26               ; Length of our DPT
+               cmp [es:di],cx
+               jb .overrun
+
+               ; This should be done by the installer...
+               mov eax,[DiskSize]
+               mov [si+16],eax
+
+               mov si,EDD_DPT
+               rep movsb
+
+               xor ax,ax
+               ret
+
+.overrun:
+               mov ax,0100h
+               ret
+%endif ; EDD
+
+               ; Set up registers as for a "Read", and compares against disk size.
+               ; WARNING: This fails immediately, even if we can transfer some
+               ; sectors.  This isn't really the correct behaviour.
 setup_regs:
 
                ; Convert a CHS address in P_CX/P_DH into an LBA in eax
@@ -359,13 +421,76 @@ setup_regs:
                add esi,[DiskBuf]       ; Get address in high memory
                cmp eax,[DiskSize]      ; Check the high mark against limit
                ja .overrun
-               shl ecx,SECTORSIZE_LG2-2 ; Convert count to 32-bit words
+               shl ecx,SECTORSIZE_LG2-2 ; Convert count to dwords
                ret
 
 .overrun:      pop ax                  ; Drop setup_regs return address
                mov ax,0200h            ; Missing address mark
                ret                     ; Return to Done
 
+               ; Set up registers as for an EDD Read, and compares against disk size.
+%if EDD
+edd_setup_regs:
+               mov si,P_SI             ; DS:SI -> DAPA
+               mov es,P_DS
+
+               mov dx,[es:si]
+               cmp dx,16
+               jb .baddapa
+
+               cmp dword [es:si+4],-1
+               je .linear_address
+
+               movzx esi,word [es:si+4]        ; Offset
+               movzx edi,word [es:si+6]        ; Segment
+               shl edi,4
+               add esi,edi
+
+               jmp .got_address
+
+.linear_address:
+               cmp dx,24                       ; Must be large enough to hold linear address
+               jb .baddapa
+
+               cmp dword [es:si+20],0          ; > 4 GB addresses not supported
+               jne .overrun
+
+               mov esi,[es:si+16]
+
+.got_address:
+               cmp dword [es:si+12],0          ; LBA too large?
+               jne .overrun
+
+               movzx ecx, word [es:si+2]       ; Sectors to transfer
+               mov edi,[es:si+8]               ; Starting sector
+               mov eax,edi
+               add eax,ecx
+               jc .overrun
+               cmp eax,[DiskSize]
+               ja .overrun
+
+               shl ecx,SECTORSIZE_LG2-2        ; Convert to dwords
+               shl edi,SECTORSIZE_LG2          ; Convert to an offset
+               add edi,[DiskBuf]
+               ret
+
+.baddapa:
+               pop ax                  ; Drop setup_regs return address
+               mov ax,0100h            ; Invalid command
+               ret
+
+.overrun:
+               and word [es:si+2],0    ; No sectors transferred
+               pop ax
+               mov ax,0200h
+               ret
+
+%endif ; EDD
+
+
+;
+; INT 15h intercept routines
+;
 int15_e820:
                cmp edx,534D4150h       ; "SMAP"
                jne near oldint15
@@ -628,7 +753,7 @@ Int13Funcs  dw Reset                ; 00h - RESET
                dw Invalid              ; 14h
                dw GetDriveType         ; 15h - GET DRIVE TYPE
                dw DetectChange         ; 16h - DETECT DRIVE CHANGE
-%if 0
+%if EDD
                dw Invalid              ; 17h
                dw Invalid              ; 18h
                dw Invalid              ; 19h
@@ -684,6 +809,20 @@ Int13Funcs dw Reset                ; 00h - RESET
 Int13FuncsEnd  equ $
 Int13FuncsMax  equ (Int13FuncsEnd-Int13Funcs) >> 1
 
+%if EDD
+EDD_DPT:
+.length                dw 26
+               ; Bit 0 - DMA boundaries handled transparently
+               ; Bit 3 - Device supports write verify
+.info          dw 0009h
+.cylinders     dd 0                    ; No physical geometry
+.heads         dd 0                    ; No physical geometry
+.sectors       dd 0                    ; No physical geometry
+.totalsize     dd 0, 0                 ; Total number of sectors
+.bytespersec   dw SECTORSIZE
+
+%endif
+
                alignb 8, db 0
 Shaker         dw ShakerEnd-$
                dd 0                    ; Pointer to self