Synchronize PCD_Infrastructure 0.55 with source code.

[mirror_edk2.git] / MdeModulePkg / Universal / PCD / Pei / Pcd.c

diff --git a/MdeModulePkg/Universal/PCD/Pei/Pcd.c b/MdeModulePkg/Universal/PCD/Pei/Pcd.c
index ecbdc946622eb92063117ddd2b00b9aec423d9d0..a998109fb9d1a77a3a68fdfb14e39a32129b3eb2 100644 (file)
--- a/MdeModulePkg/Universal/PCD/Pei/Pcd.c
+++ b/MdeModulePkg/Universal/PCD/Pei/Pcd.c
@@ -861,19 +861,28 @@ PcdUnRegisterCallBackOnSet (
 }\r
 \r
 /**\r
-  Retrieves the next valid PCD token for a given namespace.\r
-\r
-  @param[in]  Guid The 128-bit unique value that designates the namespace from which to extract the value.\r
-  @param[in, out]  TokenNumber A pointer to the PCD token number to use to find the subsequent token number.  \r
-                  If the input token namespace or token number does not exist on the platform, \r
-                  an error is returned and the value of *TokenNumber is undefined. To retrieve the "first" token, \r
-                  have the pointer reference a TokenNumber value of 0. If the input token number is 0 and \r
-                  there is no valid token number for this token namespace,  *TokenNumber will be assigned to \r
-                  0 and the function return EFI_SUCCESS. If the token number is the last valid token number, \r
-                  *TokenNumber will be assigned to 0 and the function return EFI_SUCCESS.\r
-\r
-  @retval EFI_SUCCESS  The PCD service retrieved the next valid token number. Or the input token number \r
-                        is already the last valid token number in the PCD database. \r
+  Retrieves the next valid token number in a given namespace.  \r
+  \r
+  This is useful since the PCD infrastructure contains a sparse list of token numbers, \r
+  and one cannot a priori know what token numbers are valid in the database. \r
+  \r
+  If TokenNumber is 0 and Guid is not NULL, then the first token from the token space specified by Guid is returned.  \r
+  If TokenNumber is not 0 and Guid is not NULL, then the next token in the token space specified by Guid is returned.  \r
+  If TokenNumber is 0 and Guid is NULL, then the first token in the default token space is returned.  \r
+  If TokenNumber is not 0 and Guid is NULL, then the next token in the default token space is returned.  \r
+  The token numbers in the default token space may not be related to token numbers in token spaces that are named by Guid.  \r
+  If the next token number can be retrieved, then it is returned in TokenNumber, and EFI_SUCCESS is returned.  \r
+  If TokenNumber represents the last token number in the token space specified by Guid, then EFI_NOT_FOUND is returned.  \r
+  If TokenNumber is not present in the token space specified by Guid, then EFI_NOT_FOUND is returned.\r
+\r
+\r
+  @param[in]       Guid        The 128-bit unique value that designates the namespace from which to extract the value.  \r
+                               This is an optional parameter that may be NULL.  If this parameter is NULL, then a request \r
+                               is being made to retrieve tokens from the default token space.\r
+  @param[in, out]  TokenNumber A pointer to the PCD token number to use to find the subsequent token number.\r
+                   \r
+  @retval EFI_SUCCESS   The PCD service has retrieved the next valid token number. \r
+                        Or the input token number is already the last valid token number in the PCD database. \r
                         In the later case, *TokenNumber is updated with the value of 0.\r
   @retval EFI_NOT_FOUND If this input token number and token namespace does not exist on the platform.\r
 \r