Entry ECX = Unsigned value of duration in milliseconds
EDX = Pointer to ASCII output.
Divisors dd 3600000, 60000, 1
HrsFmt db '%d:', 0
MinFmt db '%02d:', 0
SecFmt db '%06d', 0
Formats dd HrsFmt, MinFmt, SecFmt
0 57 push edi
1 56 push esi
2 53 push ebx
; Epilog set up for applications loop
3 52 push edx ; Preserve initial value
4 BE <-> mov esi, Divisors
9 8BFA mov edi, edx
B BB <-> mov ebx, Formats
10 8BD1 mov edx, ecx
12 33C9 xor ecx, ecx
14 880F mov [edi], cl ; Nullify previous contents
16 B1 03 mov cl, 3
18 51 push ecx
19 AD lodsd ; Get next divisor
1A 8BC8 mov ecx, eax
1C 8BC2 mov eax, edx
1E 33D2 xor edx, edx
20 F7F9 idiv ecx
22 8BC8 mov ecx, eax
24 87F3 xchg ebx, esi
26 AD lodsd ; Get pointer to next format string
27 87F3 xchg ebx, esi
29 23C9 and ecx, ecx
2B 75 05 jnz 32 ; Was quotient null
2D 803F 00 cmp byte ptr [edi], 0 ; Has anything been written to output
30 74 0F je 59
Write next segment of string with applicable format
32 52 push edx
33 51 push ecx
34 50 push eax
35 57 push edi
36 E8 <-> call wsprintf ; Make this segment of string
3B 83C4 0C add esp, 0C
3E 5A pop edx
3F 03F8 add edi, eax
41 59 pop ecx
42 E2 D4 loopd 19
The last part of output always has 6 characters and positions 1 & 2 must be moved to 0 & 1 and 2
replaced with the decimal point
44 8BCF mov ecx, edi
46 2BF8 sub edi, eax
48 66:8B47 01 mov ax, [edi+1]
4C 66:AB stosw
4E C607 2E mov byte ptr [edi], 2E
51 5F pop edi
52 2BCF sub ecx, edi
54 803F 30 cmp byte ptr [edi], 30
57 75 0A jnz 63
The possibility that either hours or seconds can have a leading zero and they must
be removed from output by shifting everything upward by 1
59 8BF7 mov esi, edi
5B 51 push ecx
5C 57 push edi
5D 46 inc esi
5E F3:A4 rep movsb
60 5F pop edi
61 59 pop ecx
62 49 dec ecx
Epilog ECX = Number of characters in output
EDX = Unchanged, pointer to ASCII string
63 8BD7 mov edx, edi
65 33C0 xor eax, eax
67 5B pop ebx
68 5E pop esi
69 5F pop edi
6A C3 ret
6B = 107 bytes
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