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+--- Thread: LUA : An easy way to separate an int64 into two int32 ? (/showthread.php?tid=2775)
LUA : An easy way to separate an int64 into two int32 ? - hfebraud - 05.08.2020
Hi everybody,
I'm looking for a solution to separate one data int64 into two data int32, in the aim to send energy from a smartlink (int64) via bacnet (int32).
In the device wich receive the two point int32 via Bacnet, i will aggregate this two points to reach the original value.
Thanks,
Best regards
RE: LUA : An easy way to separate an int64 into two int32 ? - admin - 05.08.2020
Which device are you using? Latest LM firmware supports int64 in BACnet.
RE: LUA : An easy way to separate an int64 into two int32 ? - hfebraud - 05.08.2020
(05.08.2020, 08:11)admin Wrote: Which device are you using? Latest LM firmware supports int64 in BACnet.It's a Wiser for KNX in 2.4.0
RE: LUA : An easy way to separate an int64 into two int32 ? - Daniel - 05.08.2020
There is a fix for this, you can send the whole int64.
https://dl.openrb.com/lmup/2020.07.14-bacnet-64bit.lmup
You may need latest fw for wiser 2.5.1
RE: LUA : An easy way to separate an int64 into two int32 ? - hfebraud - 05.08.2020
Thanks everybody, it works fine.
Solution : firmware 2.5.1 with patch is OK
I hope this can help someone else.
BR
RE: LUA : An easy way to separate an int64 into two int32 ? - Erwin van der Zwart - 05.08.2020
Hi,
And if you ever need to do a split with a 8 byte value into 2x 4 bytes you can do it like this:
Code:
value = 0xffffffff
high32 = bit.rshift(bit.band(value,0xffff0000),16)
low32 = bit.band(value,0x0000ffff)Erwin
RE: LUA : An easy way to separate an int64 into two int32 ? - admin - 05.08.2020
@Erwin, you example splits 32 bits into two 16 bit values. Lua bit operations work only with 32 bit numbers. FFI can be used to convert between different types:
Code:
function u64_to_u32(value)
local ffi = require('ffi')
local u64 = ffi.new('uint64_t[1]', value)
local u32 = ffi.new('uint32_t[2]')
ffi.copy(u32, u64, 8)
return u32[0], u32[1]
end
value = math.pow(2, 53) - 1 -- some large value
u32_l, u32_h = u64_to_u32(value)
log(u32_l, u32_h)RE: LUA : An easy way to separate an int64 into two int32 ? - Erwin van der Zwart - 05.08.2020
Aahhh, yep your right 4x8 = still 32 (:
Sorry missed that on my free day (:
RE: LUA : An easy way to separate an int64 into two int32 ? - Daniel - 05.08.2020
Admin has a free week
RE: LUA : An easy way to separate an int64 into two int32 ? - Erwin van der Zwart - 05.08.2020
He deserves it!
And he is always sharper then me so that’s not an excuse (:
BR,
Erwin