AssemblyFall2014/CEC-ExampleCodeBytes.txt at master · Amanda1223/AssemblyFall2014 · GitHub

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.data
0x00405000  94 7e b2 5d a4 71 00 00 48 65 72 65 20 69 73 20
0x00405010  74 68 65 20 73 75 6d 2c 20 70 6c 75 73 20 61 6e
0x00405020  20 65 78 74 72 61 20 33 30 30 68 20 74 6f 20 62
0x00405030  6f 6f 74 21 20

.code
0x00401010  66 c7 05 06 50 40 00 00 00 66 81 05 06 50 40 00
0x00401020  00 03 b9 06 00 00 00 be 00 50 40 00 66 0f b6 06
0x00401030  66 01 05 06 50 40 00 46 e2 f2 ba 08 50 40 00 e8
0x00401040  14 0f 00 00 0f b7 05 06 50 40 00 e8 2d 0c 00 00
0x00401050  e8 00 01 00 00 6a 00 e8 d6 0f 00 00

------------------------------------------------------------

Detailed Code Disassembly:

00401010:

MOV total_sum,0
66 C7 05		; C7 for MOV immediate word to r/m word (pg. 345, 244)
06 50 40 00		; Little Endian DWORD address of total_sum
00 00			; Hex for 0 as an immediate WORD

00401019:

ADD total_sum, 300h
66 81 05 		; 81 for ADD immediate word to r/m word (pg. 261, 244)
06 50 40 00		; Little Endian DWORD address of total_sum
00 03			; Hex for 300h as an immediate WORD (Little Endian)

00401022:

MOV ECX, LENGTHOF small_summands
b9			; B8+1 for MOV into ECX immediate DWORD (pg. 345, 246)
06 00 00 00		; Immediate DWORD = 6 (Little Endian)

00401027:

MOV ESI, OFFSET small_summands
be			; B8+6 for MOV into ESI immediate DWORD (pg. 345, 246)
00 50 40 00		; Little Endian DWORD address of small_summands

0040102C:

MOVZX AX, BYTE PTR [ESI]
66 0f b6 06		; 0F B6 for MOVZX r/m 8 into WORD register (pg. 351, 244)

00401030:

add total_sum, AX
66 01 05		; 01 for ADD  word register to r/m word (pg. 261, 244)
06 50 40 00		; Little Endian DWORD address of total_sum

00401037:

INC ESI
46			; 40+6 for INC ESI (pg. 303 and 246)

00401038:

LOOP L1
e2			; E2 for LOOP relative 8 (pg. 340)
f2			; Go *back* 14 bytes (f2h = -14 decimal)

0040103A:

MOV EDX, OFFSET msg
ba			; B8+2 for MOV into EDX immediate DWORD (pg. 345, 246)
08 50 40 00		; Little Endian DWORD address of msg

0040103F:

CALL WriteString
e8			; E8 for CALL near procedure (pg. 275)
14 0f 00 00		; Jumps ahead 0F14h=3860 bytes (where Irvine procedure has been added).

00401044:

movzx eax, total_sum
0f b7 05		; 0F B7 for MOVZX into EAX memory WORD (pg. 351, 244)
06 50 40 00		; Little Endian DWORD address of total_sum

0040104B:

Call WriteDec
e8			; E8 for CALL near procedure (pg. 275)
2d 0c 00 00		; Jumps ahead 0c2dh=3117 bytes (where Irvine procedure WriteDec has been added).

00401050:

Call Crlf
e8			; E8 for CALL near procedure (pg. 275)
00 01 00 00		; Jumps ahead 256 bytes ("Crlf" is much earlier in the alphabetical include file).