TMS570LC4357: Moving a function to RAM

jimj2713 said:

I see the RAM-allocation in the map-file, and I can single-step through the ISR (within RAM) using the debugger, but clicking run will cause data-aborts, that seem to occur at different lines of code within the ISR.

I had similar issues setting up the TMS570LC4357_sin_cos.zip example in TMS570LC4357: Fastest sin/cos code functions, where that example also copies code into RAM using a ramfunc.

The following in the main() function in source/HL_sys_main.c contains the fix applied before the program called any functions copied into RAM:

    /* In _c_int00() _cacheEnable_() is called before __TI_auto_init().
     * I.e. the cache is enabled by the time ramfuncs are copied from FLASH to SRAM, which is effectively self-modifying code.
     * Therefore, need to clean the cache to write-back the ramfuncs into SRAM so that the correct contents is loaded into the
     * instruction cache when the functions are called.
     *
     * Without this cache clean attempting to call the ramfuncs resulted in a pre-fetch abort.
     */
    cache_clean ();

And the code for the cache_clean() function is:

// Clean the data cache.
// ARM Architecture Reference Manual
// B2.2.7 (B2-1286) Performing Cache Maintenance Operations
// From https://e2e.ti.com/support/microcontrollers/arm-based-microcontrollers-group/arm-based-microcontrollers/f/arm-based-microcontrollers-forum/485953/incorrect-cache-enable-disable-procedure-in-rm57-technical-reference-manual
asm("CONST_3FF  .word 0x3ff");
asm("CONST_7FFF .word 0x00007fff");

#define CACHE_CLEAN \
    asm(" MRC p15, #1, r0, c0, c0, #1");  \
    asm(" ANDS R3, R0, #0x07000000");     \
    asm(" MOV R3, R3, LSR #23");          \
    asm(" BEQ Finished");                 \
    asm(" MOV R10, #0");                  \
    asm("Loop1:");                        \
    asm(" ADD R2, R10, R10, LSR #1");     \
    asm(" MOV R1, R0, LSR R2");           \
    asm(" AND R1, R1, #7");               \
    asm(" CMP R1, #2");                   \
    asm(" BLT Skip");                     \
    asm(" MCR p15, #2, R10, c0, c0, #0"); \
    asm(" ISB");                          \
    asm(" MRC p15, #1, R1, c0, c0, #0");  \
    asm(" AND R2, R1, #7");               \
    asm(" ADD R2, R2, #4");               \
    asm(" LDR R4,  CONST_3FF");           \
    asm(" ANDS R4, R4, R1, LSR #3");      \
    asm(" CLZ R5, R4");                   \
    asm(" MOV R9, R4");                   \
    asm("Loop2:");                        \
    asm(" LDR R7, CONST_7FFF");           \
    asm(" ANDS R7, R7, R1, LSR #13");     \
    asm("Loop3:");                        \
    asm(" ORR R11, R10, R9, LSL R5");     \
    asm(" ORR R11, R11, R7, LSL R2");     \
    asm(" MCR p15, #0, R11, c7, c10, #2");\
    asm(" SUBS R7, R7, #1");              \
    asm(" BGE Loop3");                    \
    asm(" SUBS R9, R9, #1");              \
    asm(" BGE Loop2");                    \
    asm("Skip:");                         \
    asm(" ADD R10, R10, #2");             \
    asm(" CMP R3, R10");                  \
    asm(" BGT Loop1");                    \
    asm(" DSB");                          \
    asm("Finished:")

void cache_clean(void)
{
    CACHE_CLEAN;
}