Differences

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--- mario_kart_64:eeprom_map [2016/04/10 16:16]
shygoo created
+++ mario_kart_64:eeprom_map [2017/06/23 10:49] (current)
shygoo ↷ Links adapted because of a move operation
@@ Line 5: / Line 5: @@
 ===== Top level structure =====
 ^ Offset   ^ Length ^ Description                               ^
-| 0x000    | 24     | Luigi raceway record set                  |
+| 0x000    | 24     | Luigi raceway [[#record_format|record set]] |
 | 0x018    | 24     | Moo Moo Farm record set                   |
 | 0x030    | 24     | Koopa Troopa Beach record set             |
@@ Line 21: / Line 21: @@
 | 0x150    | 24     | Banshee Boardwalk record set              |
 | 0x168    | 24     | Rainbow Road record set                   |
-| 0x180    | 4      | Unknown (Unused padding?)                 |
+| 0x180    | 4      | 50cc trophy information                   |
+| 0x181    | 4      | 100cc trophy information                  |
+| 0x182    | 4      | 150cc trophy information                  |
+| 0x183    | 4      | Extra trophy information                  |
 | 0x184    | 1      | Audio setting                             |
-| 0x185    | 1      | Unknown (Unused padding?)                 |
+| 0x185    | 1      | Unused, padding                           |
-| 0x186    | 2      | Unknown (Checksum?)                       |
+| 0x186    | 2      | [[#x186|Checksum of 0x180-0x184]]         |
-| 0x188    | 48     | Copies of all 1st records                 |
+| 0x188    | 12     | Copies of Mushroom Cup 1st Record Times   |
+| 0x194    | 12     | Copies of Flower Cup 1st Record Times     |
+| 0x1A0    | 12     | Copies of Mushroom Cup Lap Record Times   |
+| 0x1AC    | 12     | Copies of Flower Cup Lap Record Times     |
 | 0x1B8    | 6      | Unknown (Padding?)                        |
-| 0x1BE    | 2      | Unknown (Checksum?)                       |
+| 0x1BE    | 2      | [[[#x1BE_and_0x1F6|Checksum of 0x188-0x1BD]] |
-| 0x1C0    | 48     | Another 16 records (What for?)            |
+| 0x1C0    | 12     | Copies of Star Cup 1st Record Times       |
+| 0x1CC    | 12     | Copies of Special Cup 1st Record Times    |
+| 0x1D8    | 12     | Copies of Star Cup Lap Record Times       |
+| 0x1E4    | 12     | Copies of Special Cup Lap Record Times    |
 | 0x1F0    | 6      | Unknown (Padding?)                        |
-| 0x1F6    | 2      | Unknown (Checksum?)                       |
+| 0x1F6    | 2      | [[#x1BE_and_0x1F6|Checksum of 0x1C0-0x1F5]] |
 | 0x1FC    | 1      | Copy of audio setting (0x184)             |
-| 0x1FD    | 1      | Copy of Unknown (Unused padding?) (0x185) |
+| 0x1FD    | 1      | Copy of Unused, padding? (0x185)          |
-| 0x1FE    | 2      | Copy of Unknown (Checksum?) (0x186)       |
+| 0x1FE    | 2      | Copy of [[#x186|Checksum of 0x180-0x184]] |
 ===== Course record set =====
@@ Line 45: / Line 54: @@
 | 0x00C    | 3      | 5th record               |
 | 0x00F    | 3      | Best lap record          |
-| 0x012    | 3      | Records exist (00 or 01) |
+| 0x012    | 1      | Records exist (00 or 01) |
 | 0x013    | 4      | Unknown (Unused?)        |
-| 0x017    | 1      | Unknown (Checksum?)      |
+| 0x017    | 1      | [[#record_checksum|Record Checksum]] |
-{{:mk64:yjuty.png?200}}
+{{mario_kart_64:yjuty.png?200}}
 ===== Record Format =====
-Record entries are 24 bits each and are formatted in the following manner:
+Record entries are 24 bits each and are stored with little endian byte ordering:
-''<color red>tttttttt tttttttt</color> <color green>cccc</color> <color red>tttt</color>''
+''<color red>tttttttt tttttttt</color> <color green>cccc</color><color red>tttt</color>''
-Where ''<color red>t</color>'' is a 20 bit little endian value for the completion time and ''<color green>c</color>'' is a 4 bit ID of the character used in the trial. The game seems to display the time as ''((<color red>t</color> / 6000) * 10000) + (<color red>t</color> % 6000)'' in decimal notation, with the literal digits split into minutes, seconds, and centiseconds (e.g. a <color red>t</color> value of 1234 will simply display 00'12"34 and a value of 65536 will display 10'55"36). If a record has a time greater than or equal to 100 minutes, it is not displayed.
+Where ''<color red>t</color>'' is a 20 bit value for the completion time in centiseconds and ''<color green>c</color>'' is a 4 bit ID of the character used in the trial. If a record has a time greater than or equal to 100 minutes, it is not displayed.
 Valid character IDs for ''<color green>c</color>'' are as follows:
-^ ID ^ Name   ^
+^ ID ^ Character   ^
 | 0  | MARIO  |
 | 1  | LUIGI  |
@@ Line 69: / Line 78: @@
 | 6  | PEACH  |
 | 7  | BOWSER |
-| 8  | (none, unused) |
-| 9  | (none, default) |
-The default value applied to record entries is ''0xC02709'', which is 100 minutes and no character.
+The default value applied to record entries is ''0xC02709'', which is 100 minutes and Mario as the character selection.
+===== Checksums =====
+==== Record Checksum ====
+Each record contains a 1-byte checksum at offset 0x17 and is computed as follows:
+<code c>
+unsigned char RecordChecksum(unsigned char data[], int offset)
+{
+   int checksum = 0;
+   for (int rec = 0; rec < 7; rec++) {
+      for (int i = 0; i < 3; i++) {
+         unsigned char val = data[offset + rec * 3 + i];
+         checksum += (val * (i + 1)) + rec;
+      }
+   }
+   return (unsigned char)(checksum & 0xFF);
+}
+</code>
+==== 0x186 ====
+x186 is a checksum of offsets 0x180-0x184 and is computed by procedure at 800B492C and 0x187 is computed by procedure at 800B49E4
+<code c>eeprom[0x186] = (eeprom[0x180] + 1 + ((eeprom[0x181] + 1) * 2) + 1 + ((eeprom[0x182] + 1) * 3) + 2 + ((eeprom[0x183] + 1) * 4) + 3 + ((eeprom[0x184] + 1) * 5) + 4) & 0xFF
+eeprom[0x187] = (eeprom[0x186] + 0x5A) & 0xFF</code>
+==== 0x1BE and 0x1F6 ====
+<code c>
+// eeprom: base of EEPROM data
+// offset: offset in eeprom to checksum (either 0x188 or 0x1C0)
+void Checksum1BEand1F6(unsigned char eeprom[], int offset)
+{
+   int checksum = 0;
+   int blockOffset = offset;
+   for (int block = 0; block < 3; block++) {
+      int loopOffset = blockOffset + 1;
+      checksum += (eeprom[blockOffset] + 1) * (block + 1);
+      for (int byteOff = 1; byteOff < 0x11; byteOff += 0x4) {
+         int mult2 = (eeprom[loopOffset] + 1) * (block + 1);
+         checksum += mult2 + byteOff;
+         int mult3 = (eeprom[loopOffset + 1] + 1) * (block + 1);
+         checksum += mult3 + byteOff + 1;
+         int mult4 = (eeprom[loopOffset + 2] + 1) * (block + 1);
+         checksum += mult4 + byteOff + 2;
+         int mult5 = (eeprom[loopOffset + 3] + 1) * (block + 1);
+         checksum += mult5 + byteOff + 3;
+         loopOffset += 4;
+      }
+      blockOffset += 0x11;
+   }
+   eeprom[offset + 0x36] = (unsigned char)(checksum & 0xFF);
+   eeprom[offset + 0x37] = (unsigned char)((data[offset + 0x36] + 0x5A) & 0xFF);
+}
+</code>
+===== References =====
+  * http://origami64.net/showthread.php?tid=47&pid=2936#pid2936

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