Byte address becomes corrupted in simple loop

willihoffmann — Thu, 06 Nov 2014 16:03:16 GMT

Installed Products:

- CodeWarrior for MCU

Version: 10.6

Build Id:140329

I have the following Code for MC56F84769 which has a DSP56800E. It is just calculating a sum of all bytes over some range in P-Flash:

*****************************************************************************************************************************

UINT8 srvc_calc_pmem_byte_checksum_u8(UINT8 const __pmem *byte_addr_begin_pu8, UINT8 const __pmem *byte_addr_end_pu8)

{

UINT8 const __pmem *p;

UINT8 sum_u8 = 0;

for(p = byte_addr_begin_pu8; p <= byte_addr_end_pu8; ++p)

{

sum_u8 += *p;

}

return sum_u8;

}

*******************************************************************************************************************************

I'm using large data model to compile. The Compiler does the following out of it:

*****************************************************************************************************************************

;

; 635: */

; 636: UINT8 srvc_calc_pmem_byte_checksum_u8(UINT8 const __pmem *byte_addr_begin_pu8, UINT8 const __pmem *byte_addr_end_pu8)

; 637: {

; 638: UINT8 const __pmem *p;

; 639: UINT8 sum_u8 = 0;

; 640:

; 641: for(p = byte_addr_begin_pu8;

;

0x00000000 Fsrvc_calc_pmem_byte_checksum_u8:

0x00000000 0xE580 move.w #0,Y0

0x00000001 0xA90D bra *+14

;

; 643: sum_u8 += *p;

; 644: }

; 645:

; 646: return sum_u8;

;

0x00000002 0x880A moveu.w R2,R0

0x00000003 0x8D4A0001 bftsth #1,R2

0x00000005 0x8536 lsra R2

0x00000006 0x836A move.w P:(R2)+,A1

0x00000007 0xA003 bcc *+4

0x00000008 0xE700 nop

0x00000009 0xE700 nop

0x0000000A 0x5C68 asrr.w #0x000008,A

0x0000000B 0x7C02 zxt.b A,A

0x0000000C 0x8A08 moveu.w R0,R2

0x0000000D 0x7A80 add A,Y0

;

; 641: ++p)

; 642: {

;

0x0000000E 0x8172 adda #0x000001,R2

;

; 641: p <= byte_addr_end_pu8;

;

0x0000000F 0x8F33 cmpa R2,R3

0x00000010 0xA071 bcc *-14

0x00000011 0xE700 nop

;

; 647: }

;

0x00000012 0xE700 nop

0x00000013 0xE708 rts

*******************************************************************************************************************************************

You can see that at some point the Compiler uses "moveu.w R2,R0" to save R2 for later use. Because R2 holds the current address (R3 holds the end address). But R2 holds a byte address. If the byte address becomes 0x1E000 (which would be a word address 0xF000), I will lose the highest nibble of R2 because of the moveu.w instruction. Later when R0 is written back to R2, it makes R2 jump to 0xE000.

So am I doing anything wrong here? I am using large data model.

Re: Byte address becomes corrupted in simple loop

TICS_Fiona — Tue, 11 Nov 2014 03:05:15 GMT

I reproduced your problem on CodeWarrior v10.6.2. I think it is a compiler’s problem that does not create proper disassembly code. I created a SR for you to trace this problem and notify you the latest progress on it. The SR is #1-3217765578, you will receive my email today for this issue.

Please also accept our sincerest apology for this inconvenience you are experiencing with our development tool.

Best Regards

Fiona

Technical Information & Commercial Support

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Note: If this post answers your question, please click the Correct Answer button. Thank you!

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Re: Byte address becomes corrupted in simple loop

TICS_Fiona — Thu, 13 Nov 2014 03:17:43 GMT

This problem will be fixed in CW10.6.3.

Best Regards

Fiona

Technical Information & Commercial Support

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

Note: If this post answers your question, please click the Correct Answer button. Thank you!

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topic Re: Byte address becomes corrupted in simple loop in CodeWarrior for MCU

Byte address becomes corrupted in simple loop

Re: Byte address becomes corrupted in simple loop

Re: Byte address becomes corrupted in simple loop