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Type:
Bug
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Resolution: Cannot Reproduce
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Priority:
Medium
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Code Generation Tools
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CODEGEN-14238
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MSP430_21.6.1.LTS
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default
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The test case was not a bug but instead user error with managing global variables as accessed in interrupt and non-interrupt code.
The attached test case has these lines ...
unsigned long int sec_start;
/* ... */
sec_start = global_sec_count;
while((global_sec_count - sec_start) <= 3)// wait 3 seconds
{
__no_operation();
__delay_cycles( ((unsigned long int) 2000000) * 1
/ ((unsigned long int) 1));
__no_operation();
}
Build it ...
% cl430 -@options.txt file.c "file.c", line 1847: remark #1528-D: (ULP 3.1) Detected flag polling using SFRIFG1. Recommend using an interrupt combined with enter LPMx and ISR "file.c", line 1886: remark #1527-D: (ULP 2.1) Detected SW delay loop using __delay_cycles. Recommend using a timer module instead
Ignore the diagnostics. Inspect the assembly code in file.asm. Note the use of the register r13 in the last function.
The register pair r13:r12 is allocated to the local 32-bit variable sec_start. It is initialized before the start of the while loop. Inside the while loop, the register r13 is used to implement the __delay_cycles intrinsic. Then the register pair r13:r12 is compared to 3 to see whether the while loop continues. That doesn't work, because r13 now holds an unrelated value.
