Enhanced Time Processing Unit (eTPU2)MPC5644A Microcontroller Reference Manual, Rev. 6Freescale Semiconductor 99924.7.4 MISC algorithmThe MISC generator is based on the following polynomial:G(x) = 1 + x 1 + x 2 + x 22 + x 31 (equivalent to feedback mask = 0x80400007)The MISC signature generation starts by clearing the MISC Accumulator value to 0 and preloading theMISC Counter with the highest SCM address. It then steps through each address decrementing the counter,reading 32 bit values and following the algorithm below:If the least significant bit in MISC is 1 thenMISC = MISC right shifted by 1 bitMISC = MISC XOR 0x80400007elseMISC = MISC right shifted by 1 bitend ifMISC = MISC XOR RAM dataThe code example below shows an excerpt of C code that calculates the MISC signature for a given arrayof data, based on the previous algorithm:#define SCM_size (MAX_SCM_ADDRESS / 4) /* last byte address - converted to 32-bit word */#define POLY 0x80400007 /* G(x) = 1 + x 1 + x 2 + x 22 + x 31 *//*******************************************************************************FUNCTION : void calc_misc()PURPOSE : This function calculates the MISC value.INPUTS NOTES : noneRETURNS NOTES : MISC valueGENERAL NOTES : the array’unsigned int data[]’ represents the actual memoryarray, organized in 32-bit words.*******************************************************************************/unsigned int calc_misc (void){int j; /* loop counter */unsigned int misc = 0;for (j = (SCM_size-1); j >= 0 ; j--) { /* SCM_size has the number of 32-bit words in SCM */if (misc & 0x1) {misc >>= 1;misc ^= POLY;}else {misc >>= 1;}misc ^= data[j]; /* data[j] is the actual 32-bit word taken from the SCM array */}return (misc); /* final signature calculated */};The value calculated by this algorithm must be loaded into register ETPU_MISCCMPR prior to activatingthe SCM MISC calculator in eTPU. Once the MISC calculator is activated (bit SCMMISEN in register
