break;
case opid1('^'):
/*
- * ^ can be implemented as:
- * (LHS | RHS) & ~(LHS & RHS)
- * to implement ~ we need to use -1-X, as you can see the
- * whole process ends up becoming:
- * (LHS | RHS) & (-1 - (LHS & RHS))
+ * Okay lets designate what the hell is an acceptable use
+ * of the ^ operator. In many vector processing units, XOR
+ * is allowed to be used on vectors, but only if the first
+ * operand is a vector, the second operand can be a float
+ * or vector. It's never legal for the first operand to be
+ * a float, and then the following operand to be a vector.
+ * Further more, the only time it is legal to do XOR otherwise
+ * is when both operand are floats. This nicely crafted if
+ * statement catches them all.
+ *
+ * In the event that the first operand is a vector, two
+ * possible situations can arise, thus, each element of
+ * vector A (operand A) is exclusive-ORed with the corresponding
+ * element of vector B (operand B), If B is scalar, the
+ * scalar value is first replicated for each element.
+ *
+ * The QCVM itself lacks a BITXOR instruction. Thus emulating
+ * the mathematics of it is required. The following equation
+ * is used: (LHS | RHS) & ~(LHS & RHS). However, due to the
+ * QCVM also lacking a BITNEG instruction, we need to emulate
+ * ~FOO with -1 - FOO, the whole process becoming this nicely
+ * crafted expression: (LHS | RHS) & (-1 - (LHS & RHS)).
+ *
+ * When A is not scalar, this process is repeated for all
+ * components of vector A with the value in operand B,
+ * only if operand B is scalar. When A is not scalar, and B
+ * is also not scalar, this process is repeated for all
+ * components of the vector A with the components of vector B.
+ * Finally when A is scalar and B is scalar, this process is
+ * simply used once for A and B being LHS and RHS respectfully.
+ *
+ * Yes the semantics are a bit strange (no pun intended).
+ * But then again BITXOR is strange itself, consdering it's
+ * commutative, assocative, and elements of the BITXOR operation
+ * are their own inverse.
*/
- if (NotSameType(TYPE_FLOAT)) {
+ if ( !(exprs[0]->vtype == TYPE_FLOAT && exprs[1]->vtype == TYPE_FLOAT) &&
+ !(exprs[0]->vtype == TYPE_VECTOR && exprs[1]->vtype == TYPE_FLOAT) &&
+ !(exprs[0]->vtype == TYPE_VECTOR && exprs[1]->vtype == TYPE_VECTOR))
+ {
compile_error(ctx, "invalid types used in expression: cannot perform bit operations between types %s and %s",
type_name[exprs[0]->vtype],
type_name[exprs[1]->vtype]);
return false;
}
- if(CanConstFold(exprs[0], exprs[1])) {
- out = (ast_expression*)parser_const_float(parser, (float)((qcint)(ConstF(0)) ^ ((qcint)(ConstF(1)))));
- } else {
- ast_binary *expr = ast_binary_new(
- ctx,
- INSTR_SUB_F,
- (ast_expression*)parser_const_float_neg1(parser),
- (ast_expression*)ast_binary_new(
- ctx,
- INSTR_BITAND,
- exprs[0],
- exprs[1]
- )
- );
- expr->refs = AST_REF_NONE;
-
- out = (ast_expression*)
- ast_binary_new(
+ /*
+ * IF the first expression is float, the following will be too
+ * since scalar ^ vector is not allowed.
+ */
+ if (exprs[0]->vtype == TYPE_FLOAT) {
+ if(CanConstFold(exprs[0], exprs[1])) {
+ out = (ast_expression*)parser_const_float(parser, (float)((qcint)(ConstF(0)) ^ ((qcint)(ConstF(1)))));
+ } else {
+ ast_binary *expr = ast_binary_new(
ctx,
- INSTR_BITAND,
+ INSTR_SUB_F,
+ (ast_expression*)parser_const_float_neg1(parser),
(ast_expression*)ast_binary_new(
ctx,
- INSTR_BITOR,
+ INSTR_BITAND,
exprs[0],
exprs[1]
- ),
- (ast_expression*)expr
+ )
);
+ expr->refs = AST_REF_NONE;
+
+ out = (ast_expression*)
+ ast_binary_new(
+ ctx,
+ INSTR_BITAND,
+ (ast_expression*)ast_binary_new(
+ ctx,
+ INSTR_BITOR,
+ exprs[0],
+ exprs[1]
+ ),
+ (ast_expression*)expr
+ );
+ }
+ } else {
+ /*
+ * The first is a vector: vector is allowed to xor with vector and
+ * with scalar, branch here for the second operand.
+ */
+ if (exprs[1]->vtype == TYPE_VECTOR) {
+ /*
+ * Xor all the values of the vector components against the
+ * vectors components in question.
+ */
+ if (CanConstFold(exprs[0], exprs[1])) {
+ out = (ast_expression*)parser_const_vector_f(
+ parser,
+ (float)(((qcint)(ConstV(0).x)) ^ ((qcint)(ConstV(1).x))),
+ (float)(((qcint)(ConstV(0).y)) ^ ((qcint)(ConstV(1).y))),
+ (float)(((qcint)(ConstV(0).z)) ^ ((qcint)(ConstV(1).z)))
+ );
+ } else {
+ compile_error(ast_ctx(exprs[0]), "Not Yet Implemented: bit-xor for vector against vector");
+ return false;
+ }
+ } else {
+ /*
+ * Xor all the values of the vector components against the
+ * scalar in question.
+ */
+ if (CanConstFold(exprs[0], exprs[1])) {
+ out = (ast_expression*)parser_const_vector_f(
+ parser,
+ (float)(((qcint)(ConstV(0).x)) ^ ((qcint)(ConstF(1)))),
+ (float)(((qcint)(ConstV(0).y)) ^ ((qcint)(ConstF(1)))),
+ (float)(((qcint)(ConstV(0).z)) ^ ((qcint)(ConstF(1))))
+ );
+ } else {
+ compile_error(ast_ctx(exprs[0]), "Not Yet Implemented: bit-xor for vector against float");
+ return false;
+ }
+ }
}
+
break;
case opid2('<','<'):
vec_free(parser->correct_variables);
vec_free(parser->correct_variables_score);
-
for (i = 0; i < vec_size(parser->_typedefs); ++i)
ast_delete(parser->_typedefs[i]);
vec_free(parser->_typedefs);
ast_value_delete(parser->const_vec[0]);
ast_value_delete(parser->const_vec[1]);
ast_value_delete(parser->const_vec[2]);
+
+ if (parser->reserved_version)
+ ast_value_delete(parser->reserved_version);
util_htdel(parser->aliases);
intrin_intrinsics_destroy(parser);
projects / xonotic / gmqcc.git / blobdiff