core: Add func wcore_attrib_list_pop()

This is useful for removing attributes as they are parsed.

Signed-off-by: Chad Versace <chad.versace@intel.com>
Tested-by: Emil Velikov <emil.l.velikov@gmail.com> (msvc/wgl)
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>

2 files changed, 46 insertions, 0 deletions

diff --git a/src/waffle/core/wcore_attrib_list.c b/src/waffle/core/wcore_attrib_list.c
index 6446ca0..985e13a 100644
--- a/src/waffle/core/wcore_attrib_list.c
+++ b/src/waffle/core/wcore_attrib_list.c
@@ -204,3 +204,43 @@ wcore_attrib_list_copy(const intptr_t attrib_list[])
 
     return copy;
 }
+
+bool
+wcore_attrib_list_pop(
+        intptr_t attrib_list[],
+        intptr_t key,
+        intptr_t *value)
+{
+    // Address of key in attrib_list.
+    intptr_t *key_addr = NULL;
+
+    // Address of the terminal zero in attrib_list.
+    intptr_t *end_addr = NULL;
+
+    if (attrib_list == NULL) {
+        return false;
+    }
+
+    for (intptr_t *i = attrib_list; *i != 0; i += 2) {
+        if (i[0] == key) {
+            key_addr = i;
+            *value = i[1];
+            break;
+        }
+    }
+
+    if (!key_addr) {
+        return false;
+    }
+
+    end_addr = key_addr + 2; // Step to next pair.
+    while (*end_addr != 0) {
+        end_addr += 2; // Step to next pair.
+    }
+
+    // Move all key/value pairs located at or above (key_addr + 2), and
+    // move the terminal null too.
+    memmove(key_addr, key_addr + 2,
+            sizeof(intptr_t) * (end_addr - key_addr - 1));
+    return true;
+}
diff --git a/src/waffle/core/wcore_attrib_list.h b/src/waffle/core/wcore_attrib_list.h
index d4a771b..561fb1d 100644
--- a/src/waffle/core/wcore_attrib_list.h
+++ b/src/waffle/core/wcore_attrib_list.h
@@ -54,6 +54,12 @@ wcore_attrib_list_get_with_default(
         intptr_t default_value);
 
 bool
+wcore_attrib_list_pop(
+        intptr_t attrib_list[],
+        intptr_t key,
+        intptr_t *value);
+
+bool
 wcore_attrib_list_update(
         intptr_t *attrib_list,
         intptr_t key,