83Plus:BCALLs:8090

Synopsis

Official Name: MD5Update

Other Name: CalculateMD5

BCALL Address: 8090

Calculates the MD5 checksum

Inputs

• BC: The length of the data
• HL: The location of the data

Outputs

• 8269: (8 bytes) Holds the length in bits of the data hashed so far.
• 8292: (16 bytes) Will be changed to contain the new (incremental) MD5 hash of the data you gave it

Destroys

• 8259: (16 bytes) Alternate registers (roughly equivalent to the AA, BB, CC, and DD registers specified in the MD5 standard.)
• 83A5: (64 bytes) Buffer holding data to be hashed.

Comments

This B_CALL incrementally changes the MD5 "registers" for the data you give it. Note that the registers must be initialized using MD5Init first. You can call this B_CALL as many times as you want to add many separate chunks of data to the hash. To complete the MD5 hash, use MD5Final.

Example

B_CALL MD5Init
ld bc,14
ld hl,String
B_CALL MD5Update
B_CALL MD5Final
; should give: f96b697d7cb7938d525a2f31aaf161d0

String: .db "message digest"

Credits and Contributions

• FloppusMaximus: For testing that this B_CALL also work with lengths unequal to 64 bytes