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Change internal type for seeds to s32

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This fixes value truncation (and therefore incompatibility) on platforms
with an LP32 data model, such as VAX or MS-DOS.
This commit is contained in:
kwolekr 2016-06-04 01:35:37 -04:00
parent 2060fd9cbe
commit dfbdb5bcd7
13 changed files with 68 additions and 54 deletions
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20
src/mapgen.cpp
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@ -89,11 +89,25 @@ Mapgen::Mapgen(int mapgenid, MapgenParams *params, EmergeManager *emerge) :
{
generating = false;
id = mapgenid;
seed = (int)params->seed;
water_level = params->water_level;
flags = params->flags;
csize = v3s16(1, 1, 1) * (params->chunksize * MAP_BLOCKSIZE);
/*
We are losing half our entropy by doing this, but it is necessary to
preserve reverse compatibility. If the top half of our current 64 bit
seeds ever starts getting used, existing worlds will break due to a
different hash outcome and no way to differentiate between versions.
A solution could be to add a new bit to designate that the top half of
the seed value should be used, essentially a 1-bit version code, but
this would require increasing the total size of a seed to 9 bytes (yuck)
It's probably okay if this never gets fixed. 4.2 billion possibilities
ought to be enough for anyone.
*/
seed = (s32)params->seed;
vm = NULL;
ndef = emerge->ndef;
biomegen = NULL;
@ -107,7 +121,7 @@ Mapgen::~Mapgen()
}
u32 Mapgen::getBlockSeed(v3s16 p, int seed)
u32 Mapgen::getBlockSeed(v3s16 p, s32 seed)
{
return (u32)seed +
p.Z * 38134234 +
@ -116,7 +130,7 @@ u32 Mapgen::getBlockSeed(v3s16 p, int seed)
}
u32 Mapgen::getBlockSeed2(v3s16 p, int seed)
u32 Mapgen::getBlockSeed2(v3s16 p, s32 seed)
{
u32 n = 1619 * p.X + 31337 * p.Y + 52591 * p.Z + 1013 * seed;
n = (n >> 13) ^ n;