}\r
\r
\r
+/**\r
+ Skip bytes in the firmware configuration item.\r
+\r
+ Increase the offset of the firmware configuration item without transferring\r
+ bytes between the item and a caller-provided buffer. Subsequent read, write\r
+ or skip operations will commence at the increased offset.\r
+\r
+ @param[in] Size Number of bytes to skip.\r
+**/\r
+VOID\r
+EFIAPI\r
+QemuFwCfgSkipBytes (\r
+ IN UINTN Size\r
+ )\r
+{\r
+ UINTN ChunkSize;\r
+ UINT8 SkipBuffer[256];\r
+\r
+ if (!InternalQemuFwCfgIsAvailable ()) {\r
+ return;\r
+ }\r
+\r
+ if (InternalQemuFwCfgDmaIsAvailable () && Size <= MAX_UINT32) {\r
+ InternalQemuFwCfgDmaBytes ((UINT32)Size, NULL, FW_CFG_DMA_CTL_SKIP);\r
+ return;\r
+ }\r
+\r
+ //\r
+ // Emulate the skip by reading data in chunks, and throwing it away. The\r
+ // implementation below is suitable even for phases where RAM or dynamic\r
+ // allocation is not available or appropriate. It also doesn't affect the\r
+ // static data footprint for client modules. Large skips are not expected,\r
+ // therefore this fallback is not performance critical. The size of\r
+ // SkipBuffer is thought not to exert a large pressure on the stack in any\r
+ // phase.\r
+ //\r
+ while (Size > 0) {\r
+ ChunkSize = MIN (Size, sizeof SkipBuffer);\r
+ IoReadFifo8 (0x511, ChunkSize, SkipBuffer);\r
+ Size -= ChunkSize;\r
+ }\r
+}\r
+\r
+\r
/**\r
Reads a UINT8 firmware configuration value\r
\r