1 ; Various functions for the Interaction with the FAT16 Filesystem
3 ; Copyright (C) 2010 Frank Zoll
4 ; Copyright (C) 2010 Sprite_tm
5 ; Copyright (C) 2010 Leo C.
7 ; This file is part of avrcpm.
9 ; avrcpm is free software: you can redistribute it and/or modify it
10 ; under the terms of the GNU General Public License as published by
11 ; the Free Software Foundation, either version 3 of the License, or
12 ; (at your option) any later version.
14 ; avrcpm is distributed in the hope that it will be useful,
15 ; but WITHOUT ANY WARRANTY; without even the implied warranty of
16 ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 ; GNU General Public License for more details.
19 ; You should have received a copy of the GNU General Public License
20 ; along with avrcpm. If not, see <http://www.gnu.org/licenses/>.
25 ; ============================================================================
28 ; Size of a Sector is fixed to 512 Bytes by Base - MMC Driver implementation
29 ; The Functions below therefore assume a fixed Size of 512 Bytes per Sector.
30 ; ============================================================================
35 ; ############################################################################
36 ; Defines for FAT16 Structures
37 ; ############################################################################
39 #define PARTID_FAT16 0x0E
41 /*These are the Offsets to the Variables within the Bootsector of a FAT16
44 ;#define FAT16_BSO_SECSIZE 0x0b ; Offset to Sectorsize Word
45 #define FAT16_BSO_CLUSTSZ 0x0d ; Offset to Clustersize Byte
46 #define FAT16_BSO_RESSECT 0x0e ; Offset to Number of Reserved Sectors
47 #define FAT16_BSO_VOLPTR 0x1c ; Offset to First VolumeSector
48 #define FAT16_BSO_SECPERFAT 0x16 ; Offset to Number of Sectors per Fat
49 #define FAT16_BSO_NUMFATCP 0x10 ; Offset to Ammount of FAT Copys
50 #define FAT16_BSO_NUMDIRENT 0x11 ; Offset to Max. Root Dir. Entrys
51 #define FAT16_FIRST_IMAGENAME 'A' ; First letter of filename to search
52 #define FAT16_LAST_IMAGENAME 'Z' ; Last letter of filename to search
54 ; ############################################################################
55 ; Start of Data Segment
56 ; ############################################################################
59 fat_partfound: .byte 1 ; (partition: 0= no found 1=found )
60 fat_parttbl: .byte 4 ; first fat16 partition entry
61 ; only startsector is needed
62 fat_clustersize: .byte 1 ; sectors per cluster
63 fat_numdirentrys:.byte 2 ; Max. num. of entrys within Rootdirektory
64 fat_ptr2fat: .byte 4 ; pointer to the first fat sector
65 fat_ptr2dat: .byte 4 ; pointer to the first data sector
67 /*These variables define a cache that holds the last Cluster and Sector
68 thats been searched vor. To save some of the valuabe SRAM- Space these
69 variables also are used as temporary variables by the function
72 fat_last_dsk: .byte 1 ; number of disk with entry in cache
73 fat_log_clust: .byte 2 ; last searched logical cluster
74 fat_clust_offset: .byte 1 ; offset within the cluster
75 fat_clust_ptr: .byte 4; ; sector of last real cluster
78 ; ############################################################################
79 ; Start of Code Segment
80 ; ############################################################################
83 ; ============================================================================
84 ; Function: Initialize internal FAT-Partition Variables
85 ; ============================================================================
87 ; ----------------------------------------------------------------------------
89 ; Variables : [out] fat_parttabl
90 ; ----------------------------------------------------------------------------
92 ; This Routine initializes the internal Variables, that point to the
93 ; first Found FAT16 Partition.
94 ; ============================================================================
95 fat_init_partitiontable:
106 ; ============================================================================
107 ; Function: Resets the Cache
108 ; ============================================================================
110 ; ----------------------------------------------------------------------------
112 ; Variables : [out] fat_log_clust
114 ; ----------------------------------------------------------------------------
116 ; This Routine resets the internal Cache- Variables. After reset, the
117 ; next read or write Command will initialize a scan of the FAT of
118 ; the FAT16-Partition for the given sector.
119 ; ============================================================================
123 sts fat_log_clust ,yl
124 sts fat_log_clust+1,yl
129 ; ============================================================================
130 ; Function: Saves FAT16 Partitiondata for later Scanning
131 ; ============================================================================
133 ; ----------------------------------------------------------------------------
134 ; Registers : [in] z Pointer to the Partitondata
135 ; Variables : [out] fat_partfound Boolean for "Partition found"
136 ; [out] fat_parttbl Pointer to Partitiontable
137 ; ----------------------------------------------------------------------------
139 ; This funktion sets the internal Variables to the Start and Size
140 ; of a given FAT16 Paritition. This Information will be used for a
141 ; later scanning of the Partition. See Function "fat_scan_partition"
142 ; for more information.
143 ; ============================================================================
147 printstring "fat16 part found",0
152 ; save variables on stack
156 ; set fat16 partition found flag
160 ; save data from first fat16 partition
163 ldd temp,z+PART_START
165 ldd temp,z+PART_START+1
167 ldd temp,z+PART_START+2
169 ldd temp,z+PART_START+3
172 ; reload variables from stack
178 ; ============================================================================
179 ; Read and Scann a FAT16 Partition for Imagedatefiles
180 ; ============================================================================
183 ; ----------------------------------------------------------------------------
184 ; This Routine reads the Bootblock and scanns it for a Diskimage
185 ; ============================================================================
191 printstring "fat16 scanning",0
195 ; Check if a FAT16 Partition was realy found
202 printstring "free entrys in ptable ?",0
206 ; Check for free Entrys in Partition table
212 printstring "read fat bootblock.",0
216 ; Scan partition start
223 ; Load first sector from Partition
226 breq fat_bootblock_check
228 ; Read error: Block not found
236 printstring "fat16 bootblock check",0
240 ; get sectors per cluster from bootblock
241 ldiw z,hostbuf+FAT16_BSO_CLUSTSZ
243 sts fat_clustersize,temp
246 printstring "Sectors per Cluster ",0
251 ; get num of FAT Tables from bootblock
252 ldiw z,hostbuf+FAT16_BSO_NUMFATCP
254 sts fat_last_dsk,temp ; low byte
257 printstring "Ammount of FAT copies: ",0
262 ; get max num of entrys in root direktory from bootblock
263 ldiw z,hostbuf+FAT16_BSO_NUMDIRENT
265 sts fat_numdirentrys,temp ; low byte
267 sts fat_numdirentrys+1,temp2 ; high byte
270 printstring "Max. entrys in Rootdir.: ",0
275 ; Print begin of Volume
284 printstring "Begin of Volume at: ",0
294 ; get num of sectors per FAT-Table from bootblock
295 ldiw z,hostbuf+FAT16_BSO_SECPERFAT
297 sts fat_log_clust,temp ; low byte
299 sts fat_log_clust+1,temp2 ; high byte
302 printstring "Sectors per FAT__: ",0
307 ; get num of reseved sectors from bootblock
308 ldiw z,hostbuf+FAT16_BSO_RESSECT
312 ; Calculate begin of FAT within the Volume
330 printstring "Begin of FAT at___: ",0
340 ; Calculate begin of Root- Directory within the Volume
347 lds temp ,fat_log_clust
348 lds temp2,fat_log_clust+1
349 lds temp3,fat_last_dsk
353 breq fat_calc_dp_lend
362 rjmp fat_calc_dp_loop
365 sts fat_clust_ptr ,xl
366 sts fat_clust_ptr+1,xh
367 sts fat_clust_ptr+2,yl
368 sts fat_clust_ptr+3,yh
372 printstring "Begin of DIR at___: ",0
382 ; Calculate begin of DATA Clusters within the Volume
383 ; Num. Dir.Sektors = (Num. of Dir. Entrys * 32) / Bytes per Sektor
385 ; Sectorsize is fixed at 512 Bytes, makes 16 Entrys per Sektor
387 lds zl,fat_numdirentrys ; low byte
388 lds zh,fat_numdirentrys+1 ; high byte
390 ; Num. Direntrys / 16
401 lds xh,fat_clust_ptr+1
402 lds yl,fat_clust_ptr+2
403 lds yh,fat_clust_ptr+3
416 printstring "Begin of Data at__: ",0
426 ; Here Starts the Scann of the Directory for valid image Files.
428 ; Init Image-Namecounter
429 ldi temp,FAT16_FIRST_IMAGENAME
430 sts fat_last_dsk,temp
432 fat_scan_for_next_image:
434 ; Init Offset into Directory-Sectors
436 sts fat_clust_offset,temp
438 ; Init counter for number of entry left to scan
439 lds temp,fat_numdirentrys
440 sts fat_log_clust ,temp
442 lds temp,fat_numdirentrys+1
443 sts fat_log_clust+1,temp
445 fat_next_sector_loop:
446 ; Get a Pointer to the first Directory sector
448 lds xh,fat_clust_ptr+1
449 lds yl,fat_clust_ptr+2
450 lds yh,fat_clust_ptr+3
453 lds temp,fat_clust_offset
459 ; Load sector from Directory
462 breq fat_look_for_images
464 ; Read error: Block not found
468 ; Looks at a read directory block for image entrys
503 lds temp3,fat_last_dsk ; Get actual Diskname (A to Z)
520 sts fat_clust_ptr ,zl
521 sts fat_clust_ptr+1,zh
522 sts fat_clust_ptr+2,temp2
523 rjmp fat_store_new_entry
527 lds zl ,fat_clust_ptr
528 lds zh ,fat_clust_ptr+1
529 lds temp2,fat_clust_ptr+2
535 cpi temp2,16 ; max entrys/sector
536 breq fat_scan_next_sector
537 rjmp fat_look_for_loop
539 fat_scan_next_sector:
542 lds temp3, fat_log_clust
543 lds temp4, fat_log_clust+1
548 sts fat_log_clust,temp3
549 sts fat_log_clust+1,temp4
555 lds temp,fat_clust_offset
557 sts fat_clust_offset,temp
559 rjmp fat_next_sector_loop
563 lds temp,fat_last_dsk
565 sts fat_last_dsk,temp
567 ldi temp2,FAT16_LAST_IMAGENAME
569 brge fat_scaned_last_disk
571 rjmp fat_scan_for_next_image
573 fat_scaned_last_disk:
578 ; Create new Partition Entry
581 ; Found a valid image
583 printstring "Found a valid Image ! Z=",0
597 adiw y,PARTENTRY_SIZE
599 rjmp fat_look_store_loop
602 ; Set Type of Partition to FAT16- Fileimage
607 ; Offset to Startcluster + 2
628 ; Convert Filesize to ammount of sectors
629 ; (calc with 512byte/sector)
640 ; store ammount of sectors in partitiontable
647 ; Test finding of the first sector
654 printstring "Begin of Image at: ",0
664 ; Check for another free entry in partition table
672 rjmp fat_scan_for_more
679 ; ============================================================================
680 ; Function: Cluster to HostSector
681 ; ============================================================================
682 ; Parameters: [in] xh,xl Cluster Number
683 ; [out] yh,yl,xh,xl Sector Number on Disk
684 ; ----------------------------------------------------------------------------
686 ; Variables : [used] fat_clustersize Ammount of Sectors per Cluster
688 ; ----------------------------------------------------------------------------
690 ; ! Only works with Clustersizes 2,4,8,16,32,64,128 !
691 ; ============================================================================
694 ; Get Offset into Data area of Disk
698 ; add begin of data area to offset
699 lds temp,fat_ptr2dat+0
701 lds temp,fat_ptr2dat+1
703 lds temp,fat_ptr2dat+2
705 lds temp,fat_ptr2dat+3
709 ; ============================================================================
710 ; Function: Cluster to Sector
711 ; ============================================================================
712 ; Registers: [in] xl,xh Cluster Number
713 ; [out] xl,xh,yl,yh Sector Number
714 ; Variables: [in] fat_clustersize Ammount of Sectors per Cluster
716 ; ----------------------------------------------------------------------------
718 ; Calculates the logical Sectornumber given the physical ClusterNumber
719 ; and the size of a Cluster un sectors.
721 ; ! Only works with Clustersizes 2,4,8,16,32,64,128 !
722 ; ============================================================================
728 sub xl,temp ; Substract the 2 reserved clusters
731 lds temp,fat_clustersize
748 ; ====================================================================
749 ; Function: Searches a physical Cluster, given the logical Cluster
750 ; ====================================================================
751 ; Registers: [in] xh,xl logical- Cluster
752 ; [out] yh,yl physical- Cluster
754 ; --------------------------------------------------------------------
756 ; ====================================================================
761 rcall dsk_getpartentry ; get partition entry
764 ; Get First FAT- Cluster Number of Diskimage
769 .if FAT16_DBG_FAT > 0
770 printstring "Search log. Cluster ",0
776 printstring "Search phys. Cluster ",0
786 breq fat_found_phsy_clust
787 ; Get Next Cluster from Fat
789 ; Trick: 512 Bytes Per Sector equals to 256 FAT- Entrys per Sector
790 ; so given: yl is the Offset within the FAT Sector
791 ; yh is the number off se FAT sector to Read
793 ; in zh,zl: Pointer to Word within the Sector to read
794 ; in yh..xl: Start sector number (LBA)
795 ; out zh,zl : word thats been read
799 ; Create FAT Offset Value
810 ; Add Cluster offset within sector
823 ; Check next logical Cluster
827 rjmp fat_next_phsy_clust
829 ; Found the physical cluster
830 fat_found_phsy_clust:
832 .if FAT16_DBG_FAT > 0
833 printstring "Found phys. Cluster at:",0
842 ; ============================================================================
843 ; Function: This Routine searches for the Sector within an Imagefile
844 ; ============================================================================
845 ; Registers: [out] xl,xh,yl,yh Pointer to the Sector on the SD-Card
846 ; [out] temp Error- Variable (0= No Error)
847 ; Variables: [in] hostdsk host disk #, (partition #)
848 ; [in] hostlba host block #, relative to part.start
849 ; [in] fat_last_dsk number of disk with entry in cache
850 ; [in] fat_log_clust last searched logical cluster
851 ; [in] fat_clust_offset offset within the cluster
852 ; [in] fat_clust_ptr sector of last real cluster
853 ; ----------------------------------------------------------------------------
855 ; This Routine uses the variables hostdsk and hostlba to find an Sector
857 ; The CP/M Sector given within "hostlba" are splited to a logical Cluster-
858 ; Number and the Subsector within this logical Cluster.
859 ; logical Cluster Number = hostlba / fat_clustersize
860 ; The logical Cluster Number will be compared to the logical Cluster- Number
861 ; within the Cache. When this Clusters are the same and the DiskID's are
862 ; also the same, then the cached physical Sector will be used.
863 ; When the Clusters or the Disks don't match, a seek for the physical
864 ; Cluster is performed. This seek is done thru an access over the FAT of
865 ; the FAT16 Partition. The Routine starts at the first Cluster of the
866 ; Imagefile and goes along the linked list of Clusternumber till it reaches
867 ; the searched cluster. The found Clusternumber will be used to calculate
868 ; the Sektor where this Cluster lies on the SD- Card. Both the found physical
869 ; Cluster and the logical Cluster together with the physical Sectornumber
870 ; are stored in the cache.
871 ; The last step done is to add the SubSectorOffset to the found physical
872 ; Sector. This gives the pointer to the Sector to be read and or written.
873 ; ============================================================================
879 rcall dsk_getpartentry ; get partition entry
887 ldd xl,z+5 ; get size of disk in sectors
891 cp temp,xl ; check given sector against disksize
900 ; ################# Get logical Number of Cluster within the imagefile
901 ; printstring "calc log sector"
902 ; Get logical Sectornumber from temp
907 ; Divide logical Sectornumber by size of Cluster in sectors
908 lds zl,fat_clustersize
921 rjmp fat_search_clst_lp
924 ; at this point xh and xl are carying the logical cluster number
925 ; printstring "find subsector"
926 ; ################# Get Subsector within the logical Cluster for later use
928 lds zl,fat_clustersize
932 breq fat_found_subsec
936 rjmp fat_search_clst_lp2
941 sts fat_clust_offset,zl
943 ; Check against last HOSTDISK searched
947 brne fat_wrong_cache_clst
949 ; Check against last Cluster searched
951 lds yh,fat_log_clust+1
954 brne fat_wrong_cache_clst
956 brne fat_wrong_cache_clst
958 ; Last Cluster = searched Cluster -> get Sectornumber from cache
960 lds xh,fat_clust_ptr+1
961 lds yl,fat_clust_ptr+2
962 lds yh,fat_clust_ptr+3
966 ; Cluster is not in cache, so we must search for it
967 fat_wrong_cache_clst:
971 sts fat_log_clust+1,xh
973 ; Map Logical Cluster-Number to "Physical" Cluster Number using the FAT
974 rcall fat_find_phsy_clust
976 ; Get StartSector of "physical" Cluster
981 ; Found the physical sector
982 .if FAT16_DBG_FAT > 0
983 printstring "Found phys. Sector at:",0
993 ; Save the found Sector for later use into cache
994 sts fat_clust_ptr ,xl
995 sts fat_clust_ptr+1,xh
996 sts fat_clust_ptr+2,yl
997 sts fat_clust_ptr+3,yh
999 ; Add- Subsector to Startsector
1001 lds zl,fat_clust_offset
1007 ; Found the physical sector
1008 .if FAT16_DBG_FAT > 0
1009 printstring "Sector with Offset at:",0
1023 ; ============================================================================
1024 ; Function: Does a Disk write operation
1025 ; ============================================================================
1026 ; Registers: [out] temp Error-Variable ( 0= No Error)
1027 ; Variables: [in] hostdsk host disk #, (partition #)
1028 ; [in] hostlba host block #, relative to part.start
1029 ; [in] hostbuf Sector to be written
1030 ; ----------------------------------------------------------------------------
1032 ; This Routine writes a Sector to the Imagefile inside an FAT16 Partition.
1033 ; ============================================================================
1036 .if FAT16_RWDEBUG > 1
1038 printstring "host write "
1047 rjmp fat_rdwr_err ; skip disk change detection code
1049 ; After a second thought, the following code doesn't make sense, because
1050 ; disk change (change of one or more disk images) can not reliably detected.
1051 ; At least with the existing code.
1055 rcall mgr_init_partitions
1061 call mmcWriteSect ; disabled till read is functioning
1074 ; ============================================================================
1075 ; Function: Does a Disk read operation
1076 ; ============================================================================
1078 ; Variables: [in] hostdsk host disk #, (partition #)
1079 ; [in] hostlba host block #, relative to part.start
1080 ; [out] hostbuf Sector read by this routine
1081 ; ----------------------------------------------------------------------------
1083 ; This Routine reads a Sector from the Imagefile inside an FAT16 Partition.
1084 ; ============================================================================
1087 .if FAT16_RWDEBUG > 1
1089 printstring "host read "
1096 .if FAT16_RWDEBUG > 0
1097 printstring "Read Image Sector:"
1116 rjmp fat_rdwr_err ; skip disk change detection code
1118 rcall mgr_init_partitions