From b833801ae4a0179ff29a661a9932fe0f56173d80 Mon Sep 17 00:00:00 2001
From: Francis Rowe <info@gluglug.org.uk>
Date: Sat, 10 Jan 2015 19:51:32 -0500
Subject: ich9deblob/ich9gen: re-factor the gbe checksum function

---
(limited to 'resources/utilities/ich9deblob/src/gbe/gbe.c')

diff --git a/resources/utilities/ich9deblob/src/gbe/gbe.c b/resources/utilities/ich9deblob/src/gbe/gbe.c
index 5f4cffc..9a7f44f 100644
--- a/resources/utilities/ich9deblob/src/gbe/gbe.c
+++ b/resources/utilities/ich9deblob/src/gbe/gbe.c
@@ -32,42 +32,22 @@
  * ---------------------------------------------------------------------
  */
 
-/* Read a 16-bit unsigned int from a supplied region buffer */
-uint16_t gbeGetRegionWordFrom8kBuffer(int wordOffset, uint8_t* regionData)
-{
-	int byteOffset = wordOffset << 1;
-	
-	uint16_t* regionDataWordAddress = (uint16_t*)(regionData+byteOffset);
-	uint16_t regionWord = *regionDataWordAddress;
-	
-	return regionWord;
-}
-
 /* gbe checksum calculation (algorithm based on datasheet) */
-uint16_t gbeGetChecksumFrom8kBuffer(uint8_t* regionData, uint16_t desiredValue, int byteOffset)
+uint16_t gbeGetChecksumFrom8kBuffer(uint16_t* regionData, uint16_t desiredValue, int gbeRegionBase)
 {
-	int i;
-	int wordOffset = byteOffset >> 1;
-	
-	uint16_t regionWord; /* store words here for adding to checksum */
-	uint16_t checksum = 0; /* this gbe's checksum */
+	int wordOffset;
+	uint16_t total = 0;
 
-	for (i = 0; i < 0x3F; i++) {
-		regionWord = gbeGetRegionWordFrom8kBuffer(i+wordOffset, regionData);
-		checksum += regionWord;
-	}
-	checksum = desiredValue - checksum;
+	for (wordOffset = 0; wordOffset < 0x3F; wordOffset++)
+		total += regionData[wordOffset + (gbeRegionBase>>1)];
 	
-	return checksum;
+	return desiredValue - total;
 }
 
 /* checksum calculation for 4k gbe struct (algorithm based on datasheet) */
 uint16_t gbeGetChecksumFrom4kStruct(struct GBEREGIONRECORD_4K gbeStruct4k, uint16_t desiredValue)
 {
-	uint8_t gbeBuffer4k[GBEREGIONSIZE_4K];
-	memcpy(&gbeBuffer4k, &gbeStruct4k, GBEREGIONSIZE_4K);
-	
-	return gbeGetChecksumFrom8kBuffer(gbeBuffer4k, desiredValue, 0);
+	return gbeGetChecksumFrom8kBuffer((uint16_t*)&gbeStruct4k, desiredValue, 0);
 }
 
 /* modify the gbe region extracted from a factory.rom dump */
--
cgit v0.9.1