SliTaz Repositories

     1.1 --- a/BootProg/stuff/boot32.asm	Fri Sep 23 08:28:09 2022 +0000
     1.2 +++ b/BootProg/stuff/boot32.asm	Tue Sep 27 16:21:52 2022 +0000
     1.3 @@ -80,11 +80,14 @@
     1.4  %define bx(label)       bx+label-boot
     1.5  %define si(label)       si+label-boot
     1.6  ClusterMask             equ     1               ; +9 bytes
     1.7 -NullEntryCheck          equ     1               ; +5 bytes
     1.8 +NullEntryCheck          equ     0               ; +5 bytes
     1.9  ReadRetry               equ     1               ; +7 bytes
    1.10 -LBA48bits               equ     1               ; +13 bytes
    1.11 +LBA48bits               equ     1               ; +15 bytes
    1.12  CHSsupport              equ     1               ; +27 bytes
    1.13 -CHShardDisk             equ     0               ; +11 bytes
    1.14 +CHSupTo8GB              equ     1               ; +11 bytes
    1.15 +CHSupTo32MB             equ     1               ; +7 bytes
    1.16 +SectorOf512Bytes        equ     1               ; -5 bytes
    1.17 +Always2FATs             equ     0               ; -4 bytes
    1.18  
    1.19  [BITS 16]
    1.20  
    1.21 @@ -99,6 +102,8 @@
    1.22  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
    1.23  
    1.24  boot:
    1.25 +DriveNumber             equ     boot+0
    1.26 +HiLBA                   equ     boot+2
    1.27          jmp     short   start                   ; MS-DOS/Windows checks for this jump
    1.28          nop
    1.29  bsOemName               DB      "BootProg"      ; 0x03
    1.30 @@ -136,17 +141,11 @@
    1.31  bsBackupBootSectorNo            DW      0               ; 0x32
    1.32  bsreserved             times 12 DB      0               ; 0x34
    1.33  bsDriveNumber                   DB      0               ; 0x40
    1.34 -%if LBA48bits != 0
    1.35 -HiLBA                   equ     boot+0
    1.36 -DriveNumber             equ     bsDriveNumber+0
    1.37 -%else
    1.38 -DriveNumber             equ     boot+0
    1.39 -%endif
    1.40  bsreserved1                     DB      0               ; 0x41
    1.41  bsExtendedBootSignature         DB      0               ; 0x42
    1.42  bsVolumeSerialNumber            DD      0               ; 0x43
    1.43 -bsVolumeLabel                   DB      "NO NAME    "   ; 0x47
    1.44 -bsFileSystemName                DB      "FAT32   "      ; 0x52
    1.45 +bsVolumeLabel          times 11 DB      " "             ; 0x47 "NO NAME    "
    1.46 +bsFileSystemName       times 8  DB      " "             ; 0x52 "FAT32   "
    1.47  
    1.48  ;;;;;;;;;;;;;;;;;;;;
    1.49  ;; BPB2 ends here ;;
    1.50 @@ -210,8 +209,7 @@
    1.51          pop     es
    1.52  
    1.53  RootDirReadContinue:
    1.54 -        call    ReadCluster             ; read one cluster of root dir
    1.55 -        pushf                           ; save carry="not last cluster" flag
    1.56 +        call    ReadClusterSector       ; read one sector of the root dir
    1.57  
    1.58  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
    1.59  ;; Look for the COM/EXE file to load and run ;;
    1.60 @@ -243,8 +241,9 @@
    1.61          dec     bp
    1.62          dec     bp
    1.63          jnz     FindNameCycle           ; next root entry
    1.64 -        popf                            ; restore carry="not last cluster" flag
    1.65 -        jc      RootDirReadContinue     ; continue to the next root dir cluster
    1.66 +        loop    RootDirReadContinue     ; next sector in cluster
    1.67 +        cmp     esi, 0FFFFFF6h          ; carry=0 if last cluster, and carry=1 otherwise
    1.68 +        jnc     RootDirReadContinue     ; continue to the next root dir cluster
    1.69  ErrFind:
    1.70          call    Error                   ; end of root directory (dir end reached)
    1.71          db      "File not found."
    1.72 @@ -263,7 +262,8 @@
    1.73          push    es
    1.74  FileReadContinue:
    1.75          push    di
    1.76 -        call    ReadCluster             ; read one cluster of root dir
    1.77 +        call    ReadClusterSector       ; read one sector of the boot file
    1.78 +        dec     cx
    1.79          mov     di, es
    1.80          add     di, bp
    1.81          mov     es, di                  ; es:bx updated
    1.82 @@ -350,56 +350,97 @@
    1.83  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
    1.84          retf
    1.85  
    1.86 -ReadCluster:
    1.87 +;;;;;;;;;;;;;;;;;;;;;;;;;;
    1.88 +;; Error Messaging Code ;;
    1.89 +;;;;;;;;;;;;;;;;;;;;;;;;;;
    1.90 +
    1.91 +Error:
    1.92 +        pop     si
    1.93 +puts:
    1.94 +        mov     ah, 0Eh
    1.95 +        mov     bl, 7
    1.96 +        lodsb
    1.97 +        int     10h
    1.98 +        cmp     al, '.'
    1.99 +        jne     puts
   1.100 +        cbw
   1.101 +        int     16h                     ; wait for a key...
   1.102 +        int     19h                     ; bootstrap
   1.103 +
   1.104 +Stop:
   1.105 +        hlt
   1.106 +        jmp     short Stop
   1.107 +
   1.108 +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   1.109 +;; Reads a FAT32 sector         ;;
   1.110 +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   1.111 +;; Inout:  ES:BX -> buffer      ;;
   1.112 +;;         EAX = prev sector    ;;
   1.113 +;; CX = rem sectors in cluster  ;;
   1.114 +;;         ESI = next cluster   ;;
   1.115 +;; Output: EAX = current sector ;;
   1.116 +;; CX = rem sectors in cluster  ;;
   1.117 +;;         ESI = next cluster   ;;
   1.118 +;;         BP -> para / sector  ;;
   1.119 +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   1.120 +
   1.121 +ReadClusterSector:
   1.122 +%if SectorOf512Bytes != 0
   1.123 +        mov     bp, 32                          ; bp = paragraphs per sector
   1.124 +%else
   1.125          mov     bp, [bx(bpbBytesPerSector)]
   1.126          shr     bp, 4                           ; bp = paragraphs per sector
   1.127 +%endif
   1.128          mov     dx, 1                           ; adjust LBA for next sector
   1.129          inc     cx
   1.130          loop    ReadSectorLBA
   1.131  
   1.132 -;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   1.133 -;; Reads a FAT32 cluster        ;;
   1.134 -;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   1.135 -;; Inout:  ES:BX -> buffer      ;;
   1.136 -;;           ESI = cluster no   ;;
   1.137 -;; Output:   ESI = next cluster ;;
   1.138 -;;         BP -> para / sector  ;;
   1.139 -;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   1.140 -
   1.141          mul     ebx                             ; edx:eax = 0
   1.142 +%if SectorOf512Bytes != 0
   1.143 +        mov     al, 128                         ; ax=# of FAT32 entries per sector
   1.144 +%else
   1.145          imul    ax, bp, byte 4                  ; ax=# of FAT32 entries per sector
   1.146 +%endif
   1.147          lea     edi, [esi-2]                    ; esi=cluster #
   1.148          xchg    eax, esi
   1.149          div     esi                             ; eax=FAT sector #, edx=entry # in sector
   1.150  
   1.151          imul    si, dx, byte 4                  ; si=entry # in sector, clear C
   1.152  %if LBA48bits != 0
   1.153 -        xor     dx, dx                          ; clear C
   1.154 +        xor     dx, dx
   1.155  %endif
   1.156 -        call    ReadSectorLBAabsolute           ; read 1 FAT32 sector
   1.157 +        call    ReadSectorLBAfromFAT            ; read 1 FAT32 sector
   1.158  
   1.159  %if ClusterMask != 0
   1.160          and     byte [es:si+3], 0Fh             ; mask cluster value
   1.161  %endif
   1.162          mov     esi, [es:si]                    ; esi=next cluster #
   1.163  
   1.164 +%if Always2FATs != 0
   1.165 +        imul    eax, dword [bx(bsSectorsPerFAT32)], 2
   1.166 +%else
   1.167          movzx   eax, byte [bx(bpbNumberOfFATs)]
   1.168          mul     dword [bx(bsSectorsPerFAT32)]
   1.169 +%endif
   1.170  
   1.171          xchg    eax, edi
   1.172          movzx   ecx, byte [bx(bpbSectorsPerCluster)] ; 8..128
   1.173          mul     ecx                             ; edx:eax=sector number in data area
   1.174          add     eax, edi
   1.175 +%if LBA48bits != 0
   1.176 +        adc     dx, bx
   1.177 +%endif
   1.178  
   1.179 -ReadSectorLBAabsolute:
   1.180 +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   1.181 +;; Reads a sector form the start of FAT ;;
   1.182 +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   1.183 +
   1.184 +ReadSectorLBAfromFAT:
   1.185 +        add     eax, [bx(bpbHiddenSectors)]
   1.186  %if LBA48bits != 0
   1.187          adc     dx, bx
   1.188          mov     word [bx(HiLBA)], dx
   1.189  %endif
   1.190 -        add     eax, [bx(bpbHiddenSectors)]
   1.191 -%if LBA48bits != 0
   1.192 -        adc     word [bx(HiLBA)], bx
   1.193 -%endif
   1.194          mov     dx, [bx(bpbReservedSectors)]
   1.195  
   1.196  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   1.197 @@ -432,7 +473,7 @@
   1.198          push    byte 16 ; packet size byte = 16, reserved byte = 0
   1.199  
   1.200  %if CHSsupport != 0
   1.201 -%if CHShardDisk != 0
   1.202 + %if CHSupTo8GB != 0
   1.203          push    eax
   1.204          pop     cx                      ; save low LBA
   1.205          pop     ax                      ; get high LBA
   1.206 @@ -440,12 +481,16 @@
   1.207          idiv    word [bx(bpbSectorsPerTrack)] ; up to 8GB disks, avoid divide error
   1.208  
   1.209          xchg    ax, cx                  ; restore low LBA, save high LBA / SPT
   1.210 -%else
   1.211 + %else
   1.212  ; Busybox mkdosfs creates fat32 for floppies.
   1.213  ; Floppies may support CHS only.
   1.214 +  %if CHSupTo32MB != 0
   1.215 +        xor     dx, dx                  ; clear dx (LBA offset <32MB)
   1.216 +  %else
   1.217          cwd                             ; clear dx (LBA offset <16MB)
   1.218 +  %endif
   1.219          xor     cx, cx                  ; high LBA / SPT = 0
   1.220 -%endif
   1.221 + %endif
   1.222          idiv    word [bx(bpbSectorsPerTrack)]
   1.223                  ; ax = LBA / SPT
   1.224                  ; dx = LBA % SPT         = sector - 1
   1.225 @@ -456,13 +501,13 @@
   1.226                  ; ax = (LBA / SPT) / HPC = cylinder
   1.227                  ; dx = (LBA / SPT) % HPC = head
   1.228  
   1.229 -        mov     ch, al
   1.230 +        xchg    ch, al                  ; clear al
   1.231                  ; ch = LSB 0...7 of cylinder no.
   1.232 -%if CHShardDisk != 0
   1.233 -        shl     ah, 6
   1.234 -        or      cl, ah
   1.235 + %if CHSupTo8GB != 0 || CHSupTo32MB != 0
   1.236 +        shr     ax, 2
   1.237 +        or      cl, al
   1.238                  ; cl = MSB 8...9 of cylinder no. + sector no.
   1.239 -%endif
   1.240 + %endif
   1.241          mov     dh, dl
   1.242                  ; dh = head no.
   1.243          mov     dl, [bx(DriveNumber)]   ; restore BIOS boot drive number
   1.244 @@ -482,11 +527,11 @@
   1.245          jnc     ReadSuccess             ; CF = 0 if no error
   1.246  %endif
   1.247  %if ReadRetry != 0
   1.248 -%if CHSsupport != 0
   1.249 + %if CHSsupport != 0
   1.250          cbw                             ; ah = 0 = reset function
   1.251 -%else
   1.252 + %else
   1.253          xor     ax, ax                  ; ah = 0 = reset function
   1.254 -%endif
   1.255 + %endif
   1.256          int     13h                     ; reset drive (DL)
   1.257  
   1.258          dec     bp                      ; up to 32 retries
   1.259 @@ -499,43 +544,14 @@
   1.260  ReadSuccess:
   1.261  
   1.262          popa                            ; sp += 16
   1.263 -
   1.264          popa
   1.265 -
   1.266 -        stc
   1.267 -        loop    ReadSectorNext
   1.268 -
   1.269 -        cmp     esi, 0FFFFFF6h          ; carry=0 if last cluster, and carry=1 otherwise
   1.270 -
   1.271 -ReadSectorNext:
   1.272          ret
   1.273  
   1.274  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   1.275  ;; Fill free space with zeroes ;;
   1.276  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   1.277  
   1.278 -                times (512-13-20-($-$$)) db 0
   1.279 -
   1.280 -;;;;;;;;;;;;;;;;;;;;;;;;;;
   1.281 -;; Error Messaging Code ;;
   1.282 -;;;;;;;;;;;;;;;;;;;;;;;;;;
   1.283 -
   1.284 -Error:
   1.285 -        pop     si
   1.286 -puts:
   1.287 -        mov     ah, 0Eh
   1.288 -        mov     bl, 7
   1.289 -        lodsb
   1.290 -        int     10h
   1.291 -        cmp     al, '.'
   1.292 -        jne     puts
   1.293 -        cbw
   1.294 -        int     16h                     ; wait for a key...
   1.295 -        int     19h                     ; bootstrap
   1.296 -
   1.297 -Stop:
   1.298 -        hlt
   1.299 -        jmp     short Stop
   1.300 +                times (512-13-($-$$)) db 0
   1.301  
   1.302  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   1.303  ;; Name of the file to load and run ;;