[Mesa-dev] [PATCH 4/5] Add a copy_masked_offset to copy part of a constant into another.

[Olivier Galibert]

That method is to be used to trace through assignments when computing
a constant expression.

Signed-off-by: Olivier Galibert <galibert at pobox.com>
---
 src/glsl/ir.cpp |   31 +++++++++++++++++++++++++++++++
 src/glsl/ir.h   |    8 ++++++++
 2 files changed, 39 insertions(+)

diff --git a/src/glsl/ir.cpp b/src/glsl/ir.cpp
index cfa806d..782d19a 100644
--- a/src/glsl/ir.cpp
+++ b/src/glsl/ir.cpp
@@ -857,6 +857,37 @@ ir_constant::get_record_field(const char *name)
    return (ir_constant *) node;
 }
 
+void
+ir_constant::copy_masked_offset(ir_constant *src, int offset, unsigned int mask)
+{
+  assert (!type->is_array() && !type->is_record());
+
+  if (!type->is_vector() && !type->is_matrix()) {
+     offset = 0;
+     mask = 1;
+  }
+
+  int id = 0;
+  for (int i=0; i<4; i++)
+     if(mask & (1 << i))
+	switch (this->type->base_type) {
+	case GLSL_TYPE_UINT:
+	   value.u[i+offset] = src->get_uint_component(id++);
+	   break;
+	case GLSL_TYPE_INT:
+	   value.i[i+offset] = src->get_int_component(id++);
+	   break;
+	case GLSL_TYPE_FLOAT:
+	   value.f[i+offset] = src->get_float_component(id++);
+	   break;
+	case GLSL_TYPE_BOOL:
+	   value.b[i+offset] = src->get_bool_component(id++);
+	   break;
+	default:
+	   assert(!"Should not get here.");
+	   return;
+	}
+}
 
 bool
 ir_constant::has_value(const ir_constant *c) const
diff --git a/src/glsl/ir.h b/src/glsl/ir.h
index c211880..9db6c84 100644
--- a/src/glsl/ir.h
+++ b/src/glsl/ir.h
@@ -1681,6 +1681,14 @@ public:
 
    ir_constant *get_record_field(const char *name);
 
+   /* Copy the values on another constant at a given offset and
+    * following an assign-like mask.
+    *
+    * The mask is ignored for scalars.
+    */
+
+   void copy_masked_offset(ir_constant *src, int offset, unsigned int mask);
+
    /**
     * Determine whether a constant has the same value as another constant
     *
-- 
1.7.10.280.gaa39