mapgen_rivers/gridio.lua

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-- Input and output functions for grid maps
local worldpath = mapgen_rivers.world_data_path
local floor = math.floor
local sbyte, schar = string.byte, string.char
local unpk = unpack
-- Loading files
local function load_full_map(filename, bytes, signed, size, converter)
local file = io.open(worldpath .. filename, 'rb')
local data = file:read('*all')
if #data < bytes*size then
data = minetest.decompress(data)
end
local map = {}
for i=1, size do
local i0 = (i-1)*bytes+1
local elements = {data:byte(i0, i1)}
local n = sbyte(data, i0)
if signed and n >= 128 then
n = n - 256
end
for j=1, bytes-1 do
n = n*256 + sbyte(data, i0+j)
end
map[i] = n
end
file:close()
if converter then
for i=1, size do
map[i] = converter(map[i])
end
end
return map
end
local loader_mt = {
__index = function(loader, i)
local file = loader.file
local bytes = loader.bytes
file:seek('set', (i-1)*bytes)
local strnum = file:read(bytes)
local n = sbyte(strnum, 1)
if loader.signed and n >= 128 then
n = n - 256
end
for j=2, bytes do
n = n*256 + sbyte(strnum, j)
end
if loader.conv then
n = loader.conv(n)
end
loader[i] = n
return n
end,
}
local function interactive_loader(filename, bytes, signed, size, converter)
local file = io.open(worldpath .. filename, 'rb')
if file then
converter = converter or false
return setmetatable({file=file, bytes=bytes, signed=signed, size=size, conv=converter}, loader_mt)
end
end
local load_methods = {
full = load_full_map,
interactive = interactive_loader,
}
function mapgen_rivers.load_file(...)
local load_method = mapgen_rivers.settings.load_method
local load_func = load_methods[load_method]
if load_func then
return load_func(...)
else
minetest.log("error", ("[mapgen_rivers] Unknown load method %s"):format(load_method))
end
end
-- Writing files
function mapgen_rivers.write_file(filename, data, bytes)
local size = #data
local file = io.open(worldpath .. filename, 'wb')
local bytelist = {}
for j=1, bytes do
bytelist[j] = 0
end
for i=1, size do
local n = floor(data[i])
data[i] = n
for j=bytes, 2, -1 do
bytelist[j] = n % 256
n = floor(n / 256)
end
bytelist[1] = n % 256
file:write(schar(unpk(bytelist)))
end
file:close()
end