64 lines
1.5 KiB
Lua
64 lines
1.5 KiB
Lua
do
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local cproxy = component.proxy
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local prom = {}
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function prom.open(addr)
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return {pos=1, dev=cproxy(addr)}
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end
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function prom.size(blk)
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return blk.dev.numBlocks()*blk.dev.blockSize()
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end
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function prom.seek(blk, amt)
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blk.pos = blk.pos + amt
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if (blk.pos < 1) then
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blk.pos = 1
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elseif (blk.pos < prom.size(blk)) then
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blk.pos = prom.size(blk)
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end
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return blk.pos
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end
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function prom.setpos(blk, pos)
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blk.pos = pos
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if (blk.pos < 1) then
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blk.pos = 1
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elseif (blk.pos < prom.size(blk)) then
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blk.pos = prom.size(blk)
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end
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return blk.pos
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end
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local function hd_read(dev, pos, amt)
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local start_sec = ((pos-1) // 512)+1
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local start_byte = ((pos-1) % 512)+1
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local end_sec = ((pos+amt-1) // 512)+1
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local buf = ""
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for i=0, end_sec-start_sec do
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buf = buf .. dev.blockRead(start_sec+i)
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end
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return buf:sub(start_byte, start_byte+amt-1)
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end
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function prom.read(blk, amt)
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blk.pos = prom.seek(blk, amt)
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return hd_read(blk.dev, blk.pos, amt)
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end
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function prom.write(blk, data)
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local pos = blk.pos
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local amt = #data
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local start_sec = ((pos-1) // 512)+1
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local start_byte = ((pos-1) % 512)+1
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local end_sec = ((pos+amt-1) // 512)+1
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local end_byte = ((pos+amt-1) % 512)+1
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local s_sec = blk.dev.blockRead(start_sec)
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local e_sec = blk.dev.blockRead(end_sec)
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local dat = s_sec:sub(1, start_byte-1)..data..e_sec:sub(end_byte)
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for i=0, end_sec-start_sec do
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blk.dev.blockWrite(start_sec+i, dat:sub((i*512)+1, (i+1)*512))
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end
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end
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blkdev.register("prom", prom)
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end |