C6678 DSP NaN on float-point number

The info is very vague. How the program looks like, what TI package is used, what memory region of DSP running it? How DSP returns NaN, you mean some garbage value?

Regards, Eric

Hi Eric,

Thanks for your reply!!

The code looks like:

for (int i = 0; i < n; i++) {

    c[i] =  a[i] * b[i];

}

All arrays of a, b, and c are float-float numbers.  a[i] and b[i] are initialized between 0 and 1 randomly. c[i]  is initialized as 0. The size of n could be as large as 688128 or even larger. 

Besides the NaN results when I checked in the array c, I also got +inf ... I guess it might be because of overflow??

How do you allocate the array? It is declared as static or use malloc? Maybe you can show us the CCS project we can check?

Regards, Eric

Hi, Eric,

I allocated the memory statically. 

After checking the stack size, the stack size was indeed less than the allocated memory. 

Here is the way I allocated memory globally outside any functions.

281 #pragma DATA_SECTION(x_sampt_orig, ".ddr")
284 #pragma DATA_SECTION(origx, ".ddr")
286 #pragma DATA_SECTION(ftime, ".ddr")

287 complex_t x_sampt_orig[MAX_B];
290 complex_t origx[MAX_n];
292 complex_t ftime[MAX_n];

294 #pragma DATA_ALIGN(x_sampt_orig, 128)
297 #pragma DATA_ALIGN(origx, 128)
298 #pragma DATA_ALIGN(ftime, 128)

And the linker command

15 -stack 0x8000000
16 -heap 0x8000000
17
18 MEMORY
19 {
20 LOCAL_L2_SRAM: origin = 0x00800000 length = 0x00100000 /* 1MB LOCAL L2/SRAM */
21 LOCAL_L1P_SRAM: origin = 0x00E00000 length = 0x00008000 /* 32kB LOCAL L1P/SRAM */
22 LOCAL_L1D_SRAM: origin = 0x00F00000 length = 0x00008000 /* 32kB LOCAL L1D/SRAM */
23 SHRAM: origin = 0x0C000000 length = 0x00600000 /* 6MB Multicore shared Memmory */
24
25 EMIF16_CS2: origin = 0x30000000 length = 0x04000000 /* 64MB EMIF16 CS2 Data Memory */
26 EMIF16_CS3: origin = 0x34000000 length = 0x04000000 /* 64MB EMIF16 CS3 Data Memory */
27 EMIF16_CS4: origin = 0x38000000 length = 0x04000000 /* 64MB EMIF16 CS4 Data Memory */
28 EMIF16_CS5: origin = 0x3C000000 length = 0x04000000 /* 64MB EMIF16 CS5 Data Memory */
29
30 DDR3: origin = 0x80000000 length = 0x20000000 /* 2GB CE0 and CE1 external DDR3 SDRAM */
31 }
32
33 SECTIONS
34 {
35 .text > DDR3
36 .stack > DDR3
37 .bss > DDR3
38 .cio > DDR3
39 .const > DDR3
40 .data > DDR3
41 .switch > DDR3
42 .sysmem > DDR3
43 .far > DDR3
44 .args > DDR3
45 .ppinfo > DDR3
46 .ppdata > DDR3
47
48 .pinit > DDR3
49 .cinit > DDR3
50
51 .binit > DDR3
52 .init_array > DDR3
53 .neardata > DDR3
54 .fardata > DDR3
55 .rodata > DDR3
56 .c6xabi.exidx > DDR3
57 .c6xabi.extab > DDR3
58
59 .l1sram > LOCAL_L1D_SRAM
60 .ddr > DDR3
61 .l2sram > LOCAL_L2_SRAM
62 }

I set the stack and heap size as 128 MB, which I think is way of greater than the allocated memory. 

The problems of NaN and Inf seems go away, but come with the following errors:

ERROR: x_sampt[973].re: 0.000000 (orig) != -0.001658 (opt)
ERROR: x_sampt[973].im: 0.000000 (orig) != 0.000475 (opt)
cpu opt: 2 Errors
ERROR: x_sampt[2].im: 64357.824219 (orig) != 15312665706496.002674 (opt)
ERROR: x_sampt[110].re: 0.000000 (orig) != -0.000000 (opt)

Do you have any hints?

Thanks

Cheng