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PRVM: Return NaN/inf values for divisions by zero. #246

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PRVM: Return NaN/inf values for divisions by zero. #246

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f758cf4
DIV_VF: make it slightly more correct (but slower).
divVerent Jan 6, 2025
69e2f09
Make division by 0 return NAN when output is a floating point type, n…
divVerent Jan 5, 2025
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2 changes: 2 additions & 0 deletions prvm_edict.c
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Original file line number Diff line number Diff line change
Expand Up @@ -54,6 +54,7 @@ cvar_t prvm_garbagecollection_scan_limit = {CF_CLIENT | CF_SERVER, "prvm_garbage
cvar_t prvm_garbagecollection_strings = {CF_CLIENT | CF_SERVER, "prvm_garbagecollection_strings", "1", "automatically call strunzone() on strings that are not referenced"};
cvar_t prvm_stringdebug = {CF_CLIENT | CF_SERVER, "prvm_stringdebug", "0", "Print debug and warning messages related to strings"};
cvar_t sv_entfields_noescapes = {CF_SERVER, "sv_entfields_noescapes", "wad", "Space-separated list of fields in which backslashes won't be parsed as escapes when loading entities from .bsp or .ent files. This is a workaround for buggy maps with unescaped backslashes used as path separators (only forward slashes are allowed in Quake VFS paths)."};
cvar_t prvm_gameplayfix_div0is0 = {CF_SERVER, "prvm_gameplayfix_div0is0", "0", "When set to 1, floating point division by 0 will return zero instead of returning the IEEE standardized result (likely nan or inf). Other ways of getting non-finite values are not affected, and the warning will still print."};

static double prvm_reuseedicts_always_allow = 0;
qbool prvm_runawaycheck = true;
Expand Down Expand Up @@ -3238,6 +3239,7 @@ void PRVM_Init (void)
Cvar_RegisterVariable (&prvm_garbagecollection_strings);
Cvar_RegisterVariable (&prvm_stringdebug);
Cvar_RegisterVariable (&sv_entfields_noescapes);
Cvar_RegisterVariable (&prvm_gameplayfix_div0is0);

// COMMANDLINEOPTION: PRVM: -norunaway disables the runaway loop check (it might be impossible to exit DarkPlaces if used!)
prvm_runawaycheck = !Sys_CheckParm("-norunaway");
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1 change: 1 addition & 0 deletions prvm_exec.c
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Expand Up @@ -946,6 +946,7 @@ static void PRVM_StatementCoverageEvent(prvm_prog_t *prog, mfunction_t *func, in
extern cvar_t prvm_traceqc;
extern cvar_t prvm_statementprofiling;
extern qbool prvm_runawaycheck;
extern cvar_t prvm_gameplayfix_div0is0;

#define PRVM_GLOBALSBASE 0x80000000

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62 changes: 33 additions & 29 deletions prvm_execprogram.h
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Expand Up @@ -394,16 +394,17 @@ prvm_eval_t *src;
OPC->vector[2] = tempfloat * OPA->vector[2];
DISPATCH_OPCODE();
HANDLE_OPCODE(OP_DIV_F):
if( OPB->_float != 0.0f )
{
OPC->_float = OPA->_float / OPB->_float;
}
else
if( OPB->_float == 0.0f )
{
PRE_ERROR();
VM_Warning(prog, "Attempted division of %f by zero\n", OPA->_float);
OPC->_float = 0.0f;
if (prvm_gameplayfix_div0is0.integer)
{
OPC->_float = 0;
DISPATCH_OPCODE();
}
}
OPC->_float = OPA->_float / OPB->_float;
DISPATCH_OPCODE();
HANDLE_OPCODE(OP_BITAND_F):
OPC->_float = (prvm_int_t)OPA->_float & (prvm_int_t)OPB->_float;
Expand Down Expand Up @@ -884,21 +885,22 @@ prvm_eval_t *src;
OPC->vector[2] = (prvm_vec_t) OPB->_int * OPA->vector[2];
DISPATCH_OPCODE();
HANDLE_OPCODE(OP_DIV_VF):
if( OPB->_float != 0.0f )
{
float temp = 1.0f / OPB->_float;
OPC->vector[0] = temp * OPA->vector[0];
OPC->vector[1] = temp * OPA->vector[1];
OPC->vector[2] = temp * OPA->vector[2];
}
else
if( OPB->_float == 0.0f )
{
PRE_ERROR();
VM_Warning(prog, "Attempted division of '%f %f %f' by zero\n", OPA->vector[0], OPA->vector[1], OPA->vector[2]);
OPC->vector[0] = 0.0f;
OPC->vector[1] = 0.0f;
OPC->vector[2] = 0.0f;
if (prvm_gameplayfix_div0is0.integer)
{
OPC->vector[0] = 0;
OPC->vector[1] = 0;
OPC->vector[2] = 0;
DISPATCH_OPCODE();
}
}
tempfloat = OPB->_float;
OPC->vector[0] = OPA->vector[0] / tempfloat;
OPC->vector[1] = OPA->vector[1] / tempfloat;
OPC->vector[2] = OPA->vector[2] / tempfloat;
DISPATCH_OPCODE();
HANDLE_OPCODE(OP_DIV_I):
// NOTE: This also catches the second kind of division that can trap, namely, -2147483648 / -1,
Expand All @@ -915,28 +917,30 @@ prvm_eval_t *src;
}
DISPATCH_OPCODE();
HANDLE_OPCODE(OP_DIV_IF):
if( OPB->_float != 0.0f )
{
OPC->_float = ((prvm_vec_t) OPA->_int) / OPB->_float;
}
else
if( OPB->_float == 0.0f )
{
PRE_ERROR();
VM_Warning(prog, "Attempted division of %"PRVM_PRIi" by zero\n", OPA->_int);
OPC->_float = 0;
if (prvm_gameplayfix_div0is0.integer)
{
OPC->_float = 0;
DISPATCH_OPCODE();
}
}
OPC->_float = ((prvm_vec_t) OPA->_int) / OPB->_float;
DISPATCH_OPCODE();
HANDLE_OPCODE(OP_DIV_FI):
if( OPB->_int != 0 )
{
OPC->_float = OPA->_float / (prvm_vec_t) OPB->_int;
}
else
if( OPB->_int == 0 )
{
PRE_ERROR();
VM_Warning(prog, "Attempted division of %f by zero\n", OPA->_float);
OPC->_float = 0;
if (prvm_gameplayfix_div0is0.integer)
{
OPC->_float = 0;
DISPATCH_OPCODE();
}
}
OPC->_float = OPA->_float / (prvm_vec_t) OPB->_int;
DISPATCH_OPCODE();
HANDLE_OPCODE(OP_CONV_ITOF):
OPC->_float = OPA->_int;
Expand Down
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