C podozrenie na bug compilera

[Stano]

Keil MDK470a
    uint16_t radress, rquantity;

    buf[0] = 0x87;
    buf[1] = 0x65;
    buf[2] = 0x43;
    buf[3] = 0x21;
    radress = (uint16_t)buf[0] << 8;
    radress |= buf[1];
    rquantity = (uint16_t)buf[2] << 8;
    rquantity |= buf[3];

prelozil ako:
   382:         buf[0] = 0x87;
0x08000B82 2087      MOVS     r0,#0x87
0x08000B84 7020      STRB     r0,[r4,#0x00]
   383:         buf[1] = 0x65;
0x08000B86 2065      MOVS     r0,#0x65
0x08000B88 7060      STRB     r0,[r4,#0x01]
   384:         buf[2] = 0x43;
0x08000B8A 2043      MOVS     r0,#0x43
0x08000B8C 70A0      STRB     r0,[r4,#0x02]
   385:         buf[3] = 0x21;
0x08000B8E 2021      MOVS     r0,#0x21
0x08000B90 70E0      STRB     r0,[r4,#0x03]
   386:         radress = (uint16_t)buf[0] << 8;
0x08000B92 7820      LDRB     r0,[r4,#0x00]
0x08000B94 0200      LSLS     r0,r0,#8
0x08000B96 9003      STR      r0,[sp,#0x0C]
   387:         radress |= buf[1];
0x08000B98 7860      LDRB     r0,[r4,#0x01]
0x08000B9A 9903      LDR      r1,[sp,#0x0C]
0x08000B9C 4308      ORRS     r0,r0,r1
0x08000B9E 9003      STR      r0,[sp,#0x0C]
   388:         rquantity = (uint16_t)buf[2] << 8;
0x08000BA0 78A0      LDRB     r0,[r4,#0x02]
0x08000BA2 0205      LSLS     r5,r0,#8
   389:         rquantity |= buf[3];
0x08000BA4 78E0      LDRB     r0,[r4,#0x03]
0x08000BA6 4305      ORRS     r5,r5,r0

rquantity je OK, radress hodnota 0x0001
MCU core cortex M0

Jan Waclawek  wrote / napísal(a):
> Aky kompilator, aka verzia, ake su command-line options, ako vyzera
> disassembly funkcie?
>
> wek
>
>
>
> ----- Original Message ---------------
>
>
>
>   
>> Zdravim konferenci, mam nasledovny problem:
>>
>> void funkcia (uint8_t *buf, uint8_t len, uint32_t *coils){
>>    uint16_t radr;
>>    radr = buf[0];
>>    ...
>> }
>>
>> A v debuggeri do radr priradi 0x0102, cize 16bit cislo. Optimalizacie su 
>> vypnute a priznam sa, nechapem.
>> Ako je nieco take vobec mozne?
>>     
>
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