136 lines
4.1 KiB
Plaintext
136 lines
4.1 KiB
Plaintext
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' This code is extracted from FSRW 2.6
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con
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SECTORSIZE = 512
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SECTORSHIFT = 9
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DIRSHIFT = 5
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SPI_engine_cog = 0
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SPI_command = 1
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SPI_block_index = 2
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SPI_buffer_address = 3
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SD_rootdir = 4
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SD_filesystem = 5
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SD_clustershift = 6
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SD_dataregion = 7
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SD_fat1 = 8
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SD_sectorsperfat = 9
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SD_currdir = 10
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ERR_BLOCK_NOT_LONG_ALIGNED = -4
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ERR_SPI_ENGINE_NOT_RUNNING = -999
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obj
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sdspi : "safe_spi"
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dat
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pdate long 0
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lastread long 0
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dirty long 0
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filesystem long 0
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clustershift long 0
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clustersize long 0
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fat1 long 0
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sectorsperfat long 0
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dataregion long 0
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rootdir long 0
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rootdirend long 0
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endofchain long 0
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totclusters long 0
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buf byte 0[512]
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pri brword(b)
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'
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' Read a byte-reversed word from a (possibly odd) address.
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'
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return (byte[b]) + ((byte[b][1]) << 8)
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pri brlong(b)
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'
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' Read a byte-reversed long from a (possibly odd) address.
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'
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return brword(b) + (brword(b+2) << 16)
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pri getfstype : r
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if (brlong(@buf+$36) == constant("F" + ("A" << 8) + ("T" << 16) + ("1" << 24)) and buf[$3a]=="6")
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return 1
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if (brlong(@buf+$52) == constant("F" + ("A" << 8) + ("T" << 16) + ("3" << 24)) and buf[$56]=="2")
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return 2
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' return r (default return)
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pub mount_explicit(spi_vars, DO, CLK, DI, CS) : r | start, sectorspercluster, reserved, rootentries, sectors
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{{
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' Mount a volume. The address passed in is passed along to the block
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' layer; see the currently used block layer for documentation. If the
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' volume mounts, a 0 is returned, else abort is called.
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}}
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if (pdate == 0)
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pdate := constant(((2009-1980) << 25) + (1 << 21) + (27 << 16) + (7 << 11))
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'unmount
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sdspi.start_explicit(spi_vars, DO, CLK, DI, CS)
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lastread := -1
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dirty := 0
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readblock(spi_vars, 0, @buf)
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if (getfstype > 0)
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start := 0
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else
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start := brlong(@buf+$1c6)
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readblock(spi_vars, start, @buf)
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filesystem := getfstype
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if (filesystem == 0)
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abort(-20) ' not a fat16 or fat32 volume
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if (brword(@buf+$0b) <> SECTORSIZE)
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abort(-21) ' bad bytes per sector
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sectorspercluster := buf[$0d]
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if (sectorspercluster & (sectorspercluster - 1))
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abort(-22) ' bad sectors per cluster
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clustershift := 0
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repeat while (sectorspercluster > 1)
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clustershift++
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sectorspercluster >>= 1
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sectorspercluster := 1 << clustershift
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clustersize := SECTORSIZE << clustershift
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reserved := brword(@buf+$0e)
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if (buf[$10] <> 2)
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abort(-23) ' not two FATs
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sectors := brword(@buf+$13)
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if (sectors == 0)
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sectors := brlong(@buf+$20)
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fat1 := start + reserved
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if (filesystem == 2)
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rootentries := 16 << clustershift
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sectorsperfat := brlong(@buf+$24)
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dataregion := (fat1 + 2 * sectorsperfat) - 2 * sectorspercluster
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rootdir := (dataregion + (brword(@buf+$2c) << clustershift)) << SECTORSHIFT
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rootdirend := rootdir + (rootentries << DIRSHIFT)
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endofchain := $ffffff0
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else
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rootentries := brword(@buf+$11)
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sectorsperfat := brword(@buf+$16)
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rootdir := (fat1 + 2 * sectorsperfat) << SECTORSHIFT
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rootdirend := rootdir + (rootentries << DIRSHIFT)
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dataregion := 1 + ((rootdirend - 1) >> SECTORSHIFT) - 2 * sectorspercluster
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endofchain := $fff0
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if (brword(@buf+$1fe) <> $aa55)
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abort(-24) ' bad FAT signature
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totclusters := ((sectors - dataregion + start) >> clustershift)
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long[spi_vars][SD_rootdir] := rootdir >> SECTORSHIFT
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long[spi_vars][SD_filesystem] := filesystem
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long[spi_vars][SD_clustershift] := clustershift
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long[spi_vars][SD_dataregion] := dataregion
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long[spi_vars][SD_fat1] := fat1
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long[spi_vars][SD_sectorsperfat] := sectorsperfat
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long[spi_vars][SD_currdir] := rootdir >> SECTORSHIFT
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PUB readblock(spi_vars, block_index, buffer_address)
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if long[spi_vars][SPI_engine_cog] == 0
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abort ERR_SPI_ENGINE_NOT_RUNNING
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if (buffer_address & 3)
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abort ERR_BLOCK_NOT_LONG_ALIGNED
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long[spi_vars][SPI_block_index] := block_index
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long[spi_vars][SPI_buffer_address] := buffer_address
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long[spi_vars][SPI_command] := "r"
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repeat while long[spi_vars][SPI_command] == "r"
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if long[spi_vars][SPI_command] < 0
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abort SPI_command
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