Thanks for your suggestions. I checked them up.
- I don't think it is lookup2.c because 1/ I don't see shifts by 24 2/ I know it is decoding a file and would hardly see the use.
Code:
; takes 2 arguments
; R0: an argument
; R1: a string too - this is the buffer read/written from file to decode
Downsis_CallingDecoding ; CODE XREF: Downsis_DoDecode15cd+98
PUSH {R3-R7,LR}
MOVS R4, R1 ; buffer read/written
MOVS R7, R0 ; first argument
MOVS R0, R1 ; buffer read written in r0
BLX _ZNK6TDesC83PtrEv ; TDesC8::Ptr(void)
MOVS R6, R0 ; R6 contains the TDesC8 ptr for buffer read/written
LDR R0, [R4]
LSLS R5, R0, #4
LSRS R5, R5, #4 ; this is like doing: r5 = r0 << 8?
LSLS R0, R5, #0x1D ; R0 = R5 << 0x1d
BEQ loc_90D2
ADDS R0, R7, #4 ; R7+4
BLX _ZNK6TDesC83PtrEv ; TDesC8::Ptr(void)
ADDS R1, R6, R5 ; R1 = R6 + R5
SUBS R1, #8 ; R1 = R1 - 8
MOVS R2, R0
MOVS R0, R7 ; pass first argument (stored in r7)
BL Downsis_Decoding
loc_90D2 ; CODE XREF: Downsis_CallingDecoding+16
MOVS R4, #0
B loc_90EA
; ---------------------------------------------------------------------------
loc_90D6 ; CODE XREF: Downsis_CallingDecoding+48
ADDS R0, R7, #4 ; r0 = r7 + 4
BLX _ZNK6TDesC83PtrEv ; TDesC8::Ptr(void)
MOVS R2, R0
LSLS R0, R4, #3 ; r0 = r4 << 3
ADDS R1, R0, R6 ; r1 = r0 + r6
MOVS R0, R7 ; pass this function's first argument as 1st argument
; to Downsis_decoding. This argument is stored in r7
BL Downsis_Decoding
ADDS R4, R4, #1 ; increment r4 (counter)
loc_90EA ; CODE XREF: Downsis_CallingDecoding+2C
ADDS R0, R4, #1 ; r0 = r4 + 1
LSLS R0, R0, #3 ; r0 = r0 << 3
CMP R0, R5 ; compare r0 to r5
BLE loc_90D6 ; loop
TheEnd
POP {R3-R7,PC}
; End of function Downsis_CallingDecoding
Downsis_Decoding ; CODE XREF: Downsis_CallingDecoding+26p
; Downsis_CallingDecoding+3C
var_20 = -0x20
var_1C = -0x1C
var_18 = -0x18
PUSH {R1-R7,LR}
MOVS R0, #0
MOVS R3, #0
MOVS R5, #0x20
LDRB R4, [R1]
LDR R6, [R2]
ORRS R0, R4
LDRB R4, [R1,#1] ; R4 = *(R1 + 1)
LDR R7, [R2,#4]
LSLS R4, R4, #8
ORRS R0, R4
LDRB R4, [R1,#2]
MOV LR, R6
LSLS R4, R4, #0x10
ORRS R0, R4
LDRB R4, [R1,#3]
LSLS R4, R4, #0x18
ORRS R0, R4
LDRB R4, [R1,#4]
ORRS R3, R4
LDRB R4, [R1,#5]
LSLS R4, R4, #8
ORRS R3, R4
LDRB R4, [R1,#6]
LSLS R4, R4, #0x10
ORRS R3, R4
LDRB R4, [R1,#7]
STR R7, [SP,#0x20+var_18]
LSLS R4, R4, #0x18
LDR R6, [R2,#8]
ORRS R4, R3
LDR R3, =0x9E3779B9 ; magic constant used in XTEA for eg
STR R6, [SP,#0x20+var_1C]
LDR R7, [R2,#0xC]
LSLS R2, R3, #5
MOV R12, R3
STR R7, [SP,#0x20+var_20]
B loc_9086
; ---------------------------------------------------------------------------
loc_905C ; CODE XREF: Downsis_Decoding+78
LDR R6, [SP,#0x20+var_1C]
LSLS R3, R0, #4
ADDS R3, R3, R6
ADDS R6, R0, R2
LDR R7, [SP,#0x20+var_20]
EORS R3, R6
LSRS R6, R0, #5
ADDS R6, R6, R7
EORS R3, R6
SUBS R4, R4, R3
LSLS R3, R4, #4
ADDS R6, R4, R2
ADD R3, LR
LDR R7, [SP,#0x20+var_18]
EORS R3, R6
LSRS R6, R4, #5
ADDS R6, R6, R7
EORS R3, R6
SUBS R0, R0, R3
MOV R3, R12
SUBS R2, R2, R3
loc_9086 ; CODE XREF: Downsis_Decoding+4A
SUBS R5, R5, #1
BCS loc_905C
LSRS R2, R0, #8
STRB R0, [R1]
STRB R2, [R1,#1]
LSRS R2, R0, #0x10
LSRS R0, R0, #0x18
STRB R2, [R1,#2]
STRB R0, [R1,#3]
LSRS R0, R4, #8
STRB R4, [R1,#4]
STRB R0, [R1,#5]
LSRS R0, R4, #0x10
STRB R0, [R1,#6]
LSRS R0, R4, #0x18
STRB R0, [R1,#7]
POP {R1-R7,PC}
; End of function Downsis_Decoding
