Finding the Meta Blocks in an RP235X UF2 was easy enough but I hit some problems when it came to decoding them based on the description in the RP235X datasheet, page 409, section 5.9 -
There's a lack of consistency there and the first ends with ':' the second with '_' which I guess was merely a typo.
It also wasn't immediately obvious to me that the size_flag was the msb, and not lsb of the item type byte.
And I'm not sure the 'last item' is correct -When I decode the single Meta Block in my RP235X file which appears to match the example on page 409 it seems to be a count
of the number of items in the block rather than the sum of their payload data sizes.
Is that correct ?
This is my analysis of my RP235X Run from RAM code which contains just a single Meta Block -I couldn't tell what my 'Unknown Type 0' should be from looking in picobin.h. Anyone know ?
But is that otherwise correct to the extent I have decoded it so far ?
Code:
ITEM 0 | 1 | 1 | size_flag:1 (0 means 1 byte size, 1 means 2 byte size), item_type:7:ITEM 1 | 1 + s0 | 1 | size_flag:1 = 0 means 1 byte size, 1 means 2 byte size, item_type:7_It also wasn't immediately obvious to me that the size_flag was the msb, and not lsb of the item type byte.
And I'm not sure the 'last item' is correct -
Code:
LAST_ITEM | 1 + s0 + s1 | 1 | 2 | s1 + s2 (other items' size)of the number of items in the block rather than the sum of their payload data sizes.
Is that correct ?
This is my analysis of my RP235X Run from RAM code which contains just a single Meta Block -
Code:
2000015C : FFFFDED3 --. 20000160 : 10210142 | Meta Block 20000164 : 00000203 | 20000168 : 20000000 | 2000016C : 000003FF | 20000170 : 00000000 | 20000174 : AB123579 --'Code:
Meta Block - 20000160 to 20000170 20000160 : 10210142 ITEM 1 ------TT ------42 1BS_IMAGE_TYPE 42 66 ----SS-- ----01-- Data Size 01 1 --XX---- --21---- Type Specific Data 21 33 XX------ 10------ Type Specific Data 10 16 20000164 : 00000203 DATA[0] 20000168 : 20000000 ITEM 2 ------TT ------00 Unknown Type 0 00 0 ----SS-- ----00-- Data Size 00 0 --XX---- --00---- Type Specific Data 00 0 XX------ 20------ Type Specific Data 20 32 2000016C : 000003FF ITEM 3 ------TT ------FF 2BS_LAST 7F 127 --CCCC-- --0003-- Total Item Count 0003 3 ZZ------ 00------ Zero padding 20000170 : 00000000 End of Meta BlocksBut is that otherwise correct to the extent I have decoded it so far ?
Statistics: Posted by hippy — Sat Aug 17, 2024 3:34 pm — Replies 0 — Views 30