Difference between revisions of "FSPXI:ReadFileSHA256"

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| 1
 
| 1
| File(/archive?) handle lower word
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| File handle lower word
 
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| 2
 
| 2
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| 5
 
| 5
| Size of second memory block
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| Size of read buffer
 
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| 7
| Size of first memory block
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| Size of hashtable
 
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| 8
 
| 8
| (size of first mem block << 8)  <nowiki>|</nowiki> 4
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| (size of hashtable << 8)  <nowiki>|</nowiki> 4
 
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| 9
 
| 9
| Pointer to first memory block
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| Pointer to hashtable
 
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| 10
 
| 10
| (size of second mem block << 8)  <nowiki>|</nowiki> 0x14
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| (size of read buffer << 8)  <nowiki>|</nowiki> 0x14
 
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| 11
 
| 11
| Pointer to second memory block
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| Pointer to read buffer
 
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The data read are stored in the second memory block. The first memory block is filled with hashes, in an unknown manner.
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The data read are stored in the read buffer. For each 0x1000-byte block read, a SHA256 hash of the block is stored in the hashtable.
  
Reads seem to be sector-aligned (one sector = 0x1000 bytes when reading from the cart, not sure if that is true everywhere). The first memory block seems to be filled with one hash per sector read.
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It is unknown how hashing behaves if the read offset/size are not aligned to a 0x1000-byte boundary.

Revision as of 14:36, 28 March 2015

Request

Index Word Description
0 Header code [0x004D01C4]
1 File handle lower word
2 File handle upper word
3 Offset lower word
4 Offset upper word
5 Size of read buffer
6 Unknown (always 0x00001000)
7 Size of hashtable
8 (size of hashtable << 8) | 4
9 Pointer to hashtable
10 (size of read buffer << 8) | 0x14
11 Pointer to read buffer

Response

Index Word Description
0 Header code
1 Result code
2 Size read
3 4

The data read are stored in the read buffer. For each 0x1000-byte block read, a SHA256 hash of the block is stored in the hashtable.

It is unknown how hashing behaves if the read offset/size are not aligned to a 0x1000-byte boundary.