1 files changed, 65 insertions, 0 deletions
diff --git a/src/libultra_code_O2/osMempakAddrCRC.c b/src/libultra_code_O2/osMempakAddrCRC.c
new file mode 100644
index 000000000..c902651ba
--- /dev/null
+++ b/src/libultra_code_O2/osMempakAddrCRC.c
@@ -0,0 +1,65 @@
+#include "global.h"
+
+// Valid addr up to 0x7FF
+// It's the address of a block of 0x20 bytes in the mempak
+// So that means the whole mempak has a 16-bit address space
+u8 __osContAddressCrc(u16 addr) {
+    u32 addr32 = addr;
+    u32 ret = 0;
+    u32 bit;
+    s32 i;
+
+    for (bit = 0x400; bit; bit /= 2) {
+        ret *= 2;
+        if (addr32 & bit) {
+            if (ret & 0x20) {
+                ret ^= 0x14;
+            } else {
+                ++ret;
+            }
+        } else {
+            if (ret & 0x20) {
+                ret ^= 0x15;
+            }
+        }
+    }
+    for (i = 0; i < 5; ++i) {
+        ret <<= 1;
+        if (ret & 0x20) {
+            ret ^= 0x15;
+        }
+    }
+    return ret & 0x1f;
+}
+
+u8 __osContDataCrc(u8* data) {
+    s32 ret;
+    u32 bit;
+    u32 byte;
+
+    ret = 0;
+    for (byte = 0x20; byte; --byte, ++data) {
+        for (bit = 0x80; bit; bit /= 2) {
+            ret *= 2;
+            if ((*data & bit) != 0) {
+                if ((ret & 0x100) != 0) {
+                    ret ^= 0x84;
+                } else {
+                    ++ret;
+                }
+            } else {
+                if (ret & 0x100) {
+                    ret ^= 0x85;
+                }
+            }
+        }
+    }
+    do {
+        ret *= 2;
+        if (ret & 0x100) {
+            ret ^= 0x85;
+        }
+        ++byte;
+    } while (byte < 8U);
+    return ret;
+}