Mixing
Calculating an 8-bit Checksum of Hex String
I need to calculate an 8 bit checksum using javascript for a given HEX string.
I've found this site (http://easyonlineconverter.com/converters/checksum_converter.html) does it correctly but I can't seem to reproduce the same answer in my code.
Example Hex string:
6101599669594F7F13CC72F4FC942FFD8080FF0322FE8AFFFE0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA000073F2E02020207E3FFFE1656E67C13FFF7413CCBCBB
8 Bit Checksum answer: 8A
How I understand this works:
- Split the string into pairs of two hex values (e.g. 61, 01, 59, 96) and add them together: 0x61+0x01+0x59+0x96 = 97 + 1 +89 + 150 = 337.
- Convert the total to a binary representation: 337 = 0000000101010001
- Add 1: 0000000101010010
- take the 8 most significant bits: 01010010
- Flip the bits (0s becomes 1s and 1s become 0s): 10101101
- Convert back to Hex: 10101101 = AD
This issue is that the answer should be AF (Not AD)
Question: Why am i so dumb? And what am I doing wrong here?
hex checksum complement
asked Nov 20 '18 at 13:45
Nathaniel DeshpandeNathaniel Deshpande
84
add a comment |
I need to calculate an 8 bit checksum using javascript for a given HEX string.
I've found this site (http://easyonlineconverter.com/converters/checksum_converter.html) does it correctly but I can't seem to reproduce the same answer in my code.
Example Hex string:
6101599669594F7F13CC72F4FC942FFD8080FF0322FE8AFFFE0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA000073F2E02020207E3FFFE1656E67C13FFF7413CCBCBB
8 Bit Checksum answer: 8A
How I understand this works:
- Split the string into pairs of two hex values (e.g. 61, 01, 59, 96) and add them together: 0x61+0x01+0x59+0x96 = 97 + 1 +89 + 150 = 337.
- Convert the total to a binary representation: 337 = 0000000101010001
- Add 1: 0000000101010010
- take the 8 most significant bits: 01010010
- Flip the bits (0s becomes 1s and 1s become 0s): 10101101
- Convert back to Hex: 10101101 = AD
This issue is that the answer should be AF (Not AD)
Question: Why am i so dumb? And what am I doing wrong here?
hex checksum complement
asked Nov 20 '18 at 13:45
Nathaniel DeshpandeNathaniel Deshpande
84
step 5 must be placed before step 3 (so steps should be executed in order 1, 2, 5, 3, 4, 6)
– ReAl
Nov 24 '18 at 22:52
add a comment |
I need to calculate an 8 bit checksum using javascript for a given HEX string.
I've found this site (http://easyonlineconverter.com/converters/checksum_converter.html) does it correctly but I can't seem to reproduce the same answer in my code.
Example Hex string:
6101599669594F7F13CC72F4FC942FFD8080FF0322FE8AFFFE0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA000073F2E02020207E3FFFE1656E67C13FFF7413CCBCBB
8 Bit Checksum answer: 8A
How I understand this works:
- Split the string into pairs of two hex values (e.g. 61, 01, 59, 96) and add them together: 0x61+0x01+0x59+0x96 = 97 + 1 +89 + 150 = 337.
- Convert the total to a binary representation: 337 = 0000000101010001
- Add 1: 0000000101010010
- take the 8 most significant bits: 01010010
- Flip the bits (0s becomes 1s and 1s become 0s): 10101101
- Convert back to Hex: 10101101 = AD
This issue is that the answer should be AF (Not AD)
Question: Why am i so dumb? And what am I doing wrong here?
hex checksum complement
asked Nov 20 '18 at 13:45
Nathaniel DeshpandeNathaniel Deshpande
84
I need to calculate an 8 bit checksum using javascript for a given HEX string.
I've found this site (http://easyonlineconverter.com/converters/checksum_converter.html) does it correctly but I can't seem to reproduce the same answer in my code.
Example Hex string:
6101599669594F7F13CC72F4FC942FFD8080FF0322FE8AFFFE0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA0000FA000073F2E02020207E3FFFE1656E67C13FFF7413CCBCBB
8 Bit Checksum answer: 8A
How I understand this works:
- Split the string into pairs of two hex values (e.g. 61, 01, 59, 96) and add them together: 0x61+0x01+0x59+0x96 = 97 + 1 +89 + 150 = 337.
- Convert the total to a binary representation: 337 = 0000000101010001
- Add 1: 0000000101010010
- take the 8 most significant bits: 01010010
- Flip the bits (0s becomes 1s and 1s become 0s): 10101101
- Convert back to Hex: 10101101 = AD
This issue is that the answer should be AF (Not AD)
Question: Why am i so dumb? And what am I doing wrong here?
hex checksum complement
hex checksum complement
asked Nov 20 '18 at 13:45
Nathaniel DeshpandeNathaniel Deshpande
84
asked Nov 20 '18 at 13:45
Nathaniel DeshpandeNathaniel Deshpande
84
asked Nov 20 '18 at 13:45
Nathaniel DeshpandeNathaniel Deshpande
84
asked Nov 20 '18 at 13:45
Nathaniel DeshpandeNathaniel Deshpande
84
asked Nov 20 '18 at 13:45
Nathaniel DeshpandeNathaniel Deshpande
84
84
step 5 must be placed before step 3 (so steps should be executed in order 1, 2, 5, 3, 4, 6)
– ReAl
Nov 24 '18 at 22:52
add a comment |
step 5 must be placed before step 3 (so steps should be executed in order 1, 2, 5, 3, 4, 6)
– ReAl
Nov 24 '18 at 22:52
step 5 must be placed before step 3 (so steps should be executed in order 1, 2, 5, 3, 4, 6)
– ReAl
Nov 24 '18 at 22:52
step 5 must be placed before step 3 (so steps should be executed in order 1, 2, 5, 3, 4, 6)
– ReAl
Nov 24 '18 at 22:52
add a comment |
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step 5 must be placed before step 3 (so steps should be executed in order 1, 2, 5, 3, 4, 6)
– ReAl
Nov 24 '18 at 22:52