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Turn the lua sector lines hack into a macro

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This commit is contained in:
James R 2020-10-10 16:43:09 -07:00
parent 15008f31a7
commit 8bc8946be8
2 changed files with 9 additions and 1 deletions
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8
src/doomtype.h
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@ -371,4 +371,12 @@ typedef UINT32 tic_t;
#define WSTRING2(s) L ## s
#define WSTRING(s) WSTRING2 (s)
/*
A hack by Monster Iestyn: Return a pointer to a field of
a struct from a pointer to another field in the struct.
Needed for some lua shenanigans.
*/
#define FIELDFROM( type, field, have, want ) \
(void *)((intptr_t)(field) - offsetof (type, have) + offsetof (type, want))
#endif //__DOOMTYPE__

2
src/lua_maplib.c
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@ -447,7 +447,7 @@ static int sectorlines_get(lua_State *L)
// get the "linecount" by shifting our retrieved memory address of "lines" to where "linecount" is in the sector_t, then dereferencing the result
// we need this to determine the array's actual size, and therefore also the maximum value allowed as an index
// this only works if seclines is actually a pointer to a sector's lines member in memory, oh boy
numoflines = (size_t)(*(size_t *)(((size_t)seclines) - (offsetof(sector_t, lines) - offsetof(sector_t, linecount))));
numoflines = *(size_t *)FIELDFROM (sector_t, seclines, lines,/* -> */linecount);
/* OLD HACK
// check first linedef to figure which of its sectors owns this sector->lines pointer