100 lines
3.5 KiB
Lua
100 lines
3.5 KiB
Lua
local function check(buf, i, afterI)
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local checksum = 0
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while i < afterI do
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if i+60 < afterI then
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local num1, num2, num3, num4, num5, num6, num7, num8, num9, num10, num11, num12, num13, num14, num15, num16, newI = string.unpack(">I4I4I4I4I4I4I4I4I4I4I4I4I4I4I4I4", buf, i)
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i = newI
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checksum = checksum + num1 + num2 + num3 + num4 + num5 + num6 + num7 + num8 + num9 + num10 + num11 + num12 + num13 + num14 + num15 + num16
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elseif i+28 < afterI then
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local num1, num2, num3, num4, num5, num6, num7, num8, newI = string.unpack(">I4I4I4I4I4I4I4I4", buf, i)
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i = newI
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checksum = checksum + num1 + num2 + num3 + num4 + num5 + num6 + num7 + num8
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elseif i+12 < afterI then
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local num1, num2, num3, num4, newI = string.unpack(">I4I4I4I4", buf, i)
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i = newI
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checksum = checksum + num1 + num2 + num3 + num4
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else
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local num
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num, i = string.unpack(">I4", buf, i)
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checksum = checksum + num
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end
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end
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return checksum & 0xFFFFFFFF
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end
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local function log2floor(i)
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local j = 0
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if i>>8 ~= 0 then
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j = j + 8
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end
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if i>>(j+4) ~= 0 then
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j = j + 4
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end
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if i>>(j+2) ~= 0 then
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j = j + 2
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end
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if i>>(j+1) ~= 0 then
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j = j + 1
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end
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return j
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end
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return {
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write = function(magic, tables)
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local tabdata = {}
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for t, val in next, tables do
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tabdata[#tabdata+1] = {t, val .. string.rep("\0", (#val+3&~3)-#val), #val}
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end
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table.sort(tabdata, function(a,b)return a[1]<b[1]end)
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local logtabs = log2floor(#tabdata)
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local tabs = {string.pack(">c4I2I2I2I2", magic, #tabdata, 1<<logtabs+4, logtabs, #tabdata-(1<<logtabs)<<4)}
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local offset = #tabs[1]+#tabdata*16
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local checksum, headindex = check(tabs[1], 1, 1+#tabs[1])
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for i=1,#tabdata do
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local tab = tabdata[i]
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local data = tab[2]
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if tab[1] == "head" then
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headindex = i+1+#tabdata
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data = data:sub(1,8) .. '\0\0\0\0' .. data:sub(13) -- Benchmarking suggests that this is faster than a LPEG version
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end
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local thischeck = check(data, 1, 1+tab[3])
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tabs[i+1] = string.pack(">c4I4I4I4", tab[1], thischeck, offset, tab[3])
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checksum = checksum + check(tabs[i+1], 1, 17) + thischeck
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offset = offset + #data
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tabs[i+1+#tabdata] = data
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end
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if headindex then
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local data = tabs[headindex]
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data = data:sub(1,8) .. string.pack(">I4", 0xB1B0AFBA-checksum&0xFFFFFFFF) .. data:sub(13) -- Benchmarking suggests that this is faster than a LPEG version
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tabs[headindex] = data
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end
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return table.concat(tabs)
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end,
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parse = function(buf, off, fontid)
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off = off or 1
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local headMagic, numTables
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headMagic, numTables, off = string.unpack(">c4I2", buf, off)
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if headMagic == "ttcf" then
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if numTables > 2 then -- numTables is actually the major version here, 1&2 are basically equal
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error[[Unsupported TTC header version]]
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end
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headMagic, numTables, off = string.unpack(">I2I4", buf, off)
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fontid = fontid or 1
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if numTables < fontid then
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error[[There aren't that many fonts in this file]]
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end
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off = string.unpack(">I4", buf, off + (fontid-1)*4)+1
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headMagic, numTables, off = string.unpack(">c4I2", buf, off)
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end
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off = off+6
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local tables = {}
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for i=1,numTables do
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local tag, check, offset, len, newOff = string.unpack(">c4I4I4I4", buf, off)
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off = newOff
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tables[tag] = {offset+1, len}
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if offset+len > #buf then
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error[[Font file too small]]
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end
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end
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return headMagic, tables
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end,
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}
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