twos-complement

I have a string "0AAE0000463130004144430000" and I need to calculate the two's complement checksum of the hex bytes that make up the string. The formula for the example string above is Sum the values: 0A + AE + 00 + 00 + 46 + 31 + 30 + 00 + 41 + 44 + 43 + 00 + 00 = 27 (discard the overflow) Subtract the result from 0x100 = 0xD9 D9 is the correct checksum for this example, but I am having trouble getting the two digit hex values parsed out of the string in C#. My current code is below: string output = "0AAE0000463130004144430000"; long checksum = 0; char[] outputBytes = output.TrimStart(':')

Please take a look at these two pieces of pseudo-assembly code: 1) li $t0,53 sll $t1,$t0,2 srl $t2,$t0,2 sra $t3,$t0,2 print $t1 print $t2 print $t3 2) li $t0,-53 sll $t1,$t0,2 srl $t2,$t0,2 sra $t3,$t0,2 print $t1 print $t2 print $t3 in the first case the output is: 212 13 13 in the latter is: -212 107374... -14 But shouldn't : sra (-53) = - (srl 53) ? -53 = 1111111111001011 sra 2 1111111111110010(11) = -14 ^^ ^^ sign dropped extension Because the extra bits are simply dropped for both positive and negative results, the result is always rounded down if you view the shift as a division. 53 sra

I am receiving data from a gps unit via a udp packet. Lat/Lng values are in hex. Example Data 13BF71A8 = Latitude (33.1313576) BA18A506 = Longitude (-117.2790010) The documentation explains that longitude/latitude readings are measured in degrees with a 1x10^-7 degree lsb, signed 2’s complement. For the Latitude I can convert using this formula: 13BF71A8 = 331313576 * 0.0000001 = 33.1313576 This code works for Lat but not for Lng: function convertLat(h){ var latdec = parseInt(h,16); var lat = latdec * 0.0000001; return lat; } console.log("LAT: " + convertLat("13BF71A8")); I am having trouble

The 2's complement of a number which is represented by N bits is 2^N-number. For example: if number is 7 (0111) and i'm representing it using 4 bits then, 2's complement of it would be (2^N-number) i.e. (2^4 -7)=9(1001) 7==> 0111 1's compliment of 7==> 1000 1000 + 1 ------------- 1001 =====> (9) While calculating 2's complement of a number, we do following steps: 1. do one's complement of the number 2. Add one to the result of step 1. I understand that we need to do one's complement of the number because we are doing a negation operation. But why do we add the 1? This might be a silly question

So I want to represent the number -12.5 . So 12.5 equals to: 001100.100 If I don't calculate the fraction then it's simple, -12 is: 110100 But what is -12.5? is it 110100.100 ? How can I calculate this negative fraction? With decimal number systems, each number position (or column) represents (reading a number from right to left): units (which is 10^0), tens (i.e. 10^1),hundreds (i.e. 10^2), etc. With unsigned binary numbers, the base is 2, thus each position becomes (again, reading from right to left): 1 (i.e. 2^0) ,2 (i.e. 2^1), 4 (i.e. 2^2), etc. For example 2^2 (4), 2^1 (2), 2^0 (1). In