c - U-Boot: Unexpected problems porting code -
i want extend u-boot spl code fuzzy extractor logic adding code {u-boot_sources}/arch/arm/cpu/armv7/omap-common/hwinit-common.c. u-boot shall used on pandaboard es (omap4460 soc).
thus, first implemented code on x86 pc , porting arm-based pandaboard. complete code can found here (as side note "main" function s_init()):
however, expecting dozens of unexptected effects, results in either stopping during execution of code, stopping u-boot after reading u-boot.img or not sending output (and not booting) @ all.
for example, want call 2 functions (computesyndrome, decodeerrors) inside for-loop, part of function golaydecode.
for first problem please ignore code below multiline comment starting /* >>>> these lines of code below totally break u-boot. function computesyndrome in conjunction calling function golaydecode important.
the issue: if comment out both functions computesyndrome , decodeerrors works fine , os (android) booting. however, if computesyndrome not commented out , gets processed, u-boot stucks after displaying reading u-boot.img. funny thing it: if replace computesyndrome bogus function not iterating values or displaying stuff, u-boot stucks well.
furthermore, if remove multiline comment furhter below include residual code, u-boot doesn't display ony character. (1*)
i beginner regarding microprocessor programming can not figure out possible error in these 12 lines of computesyndrome function or general behaviour of u-boot @ all. (2*)
does have clue missing?
thanks, p.
1* using minicom display output of u-boot, receive on serial-usb-converter.
2* using following compiler flags make sure there no errors @ compile time: -wall -wstrict-prototypes -wdisabled-optimization -w -pedantic
void golaydecode(volatile int x[12], volatile int y[12], volatile unsigned int golayencodedsecret[30], volatile unsigned int s, volatile unsigned char repetitiondecodedsecretbits[360]){ printf("\n[i] - performing golay decoding\r\n"); volatile unsigned char secret[22] = {0}; volatile unsigned char currentbyte = 0, tmpbyte = 0; volatile unsigned int golaydecodedsecret[30] ={0}; volatile int twelvebitcounter = 0;//, j = 0, k = 0, q = 0, aux = 0, found = 0, bitcounter = 0, i_2 = 7, currentsecretencbyte = 0x00; volatile int c_hat[2] = {0}, e[2] = {0}; e[0] = s; e[1] = 0; for(twelvebitcounter = 0; twelvebitcounter < 30; twelvebitcounter+=2){ printf("computing syndrome , decoding errors bytes %03x & %03x\n", golayencodedsecret[twelvebitcounter], golayencodedsecret[twelvebitcounter+1]); computesyndrome(golayencodedsecret[twelvebitcounter], golayencodedsecret[twelvebitcounter+1], x, y, s); decodeerrors(golayencodedsecret[i], golayencodedsecret[i+1], x, y, s); } printf("\n[d] - reconstructing secret bytes\r\n"); /* >>>> these lines of code below totally break u-boot for(i = 0; < 30; i+=2){ currentsecretencbyte = golaydecodedsecret[i]; volatile int j = 11; // access each source bit for(; 0<=j; j--){ volatile int currentsourcebit = (currentsecretencbyte >> j) & 0x01; repetitiondecodedsecretbits[bitcounter] = currentsourcebit; bitcounter++; } } k = 0; for(i = 0; i<176; i++){ tmpbyte = repetitiondecodedsecretbits[i] << i_2; currentbyte = currentbyte | tmpbyte; i_2--; if(i_2==0){ // collected 8 bits , created byte secret[k] = currentbyte; i_2 = 7; tmpbyte = 0x00; currentbyte = 0x00; k++; } } sha256_ctx ctx; unsigned char hash[32]; printf("\n[i] - generating secret key k\n"); sha256_init(&ctx); sha256_update(&ctx,secret,strlen((const char*)secret)); sha256_final(&ctx,hash); printf("\n[i] - our secret key k\n\t==================================\n\t"); print_hash(hash); printf("\t==================================\n"); */ } /* function syndrome computation */ void computesyndrome(int r0, int r1, volatile int x[12], volatile int y[12], volatile unsigned int s){ unsigned int syndromebitcounter, syndromematrixcounter, syndromeaux; s = 0; for(syndromematrixcounter=0; syndromematrixcounter<12; syndromematrixcounter++){ syndromeaux = 0; for(syndromebitcounter=0; syndromebitcounter<12; syndromebitcounter++){ syndromeaux = syndromeaux^((x[syndromematrixcounter]&r0)>>syndromebitcounter &0x01); } for(syndromebitcounter=0; syndromebitcounter<12; syndromebitcounter++){ syndromeaux = syndromeaux^((y[syndromematrixcounter]&r1)>>syndromebitcounter &0x01); } s = (s<<1)^syndromeaux; } } /* funcion recover original byte */ void decodeerrors(int r0, int r1, volatile int x[12], volatile int y[12], volatile unsigned int s){ //printf("\n[d] - starting decode errors %3x | %3x\n", r0, r1); volatile unsigned int c_hat[2] = {0xaa}, e[2] = {0xaa}; volatile unsigned int q; unsigned int i, j, aux, found; //printf("step 2\n"); if(weight(s)<=3){ e[0] = s; e[1] = 0; }else{ /******* step 3 */ //printf("step 3\n"); = 0; found = 0; do{ if (weight(s^y[i]) <=2){ e[0] = s^y[i]; e[1] = x[i]; found = 1; printf("\ntest 2\n"); } i++; }while ((i<12) && (!found)); if (( i==12 ) && (!found)){ /******* step 4 */ //printf("step 4\n"); q = 0; (j=0; j<12; j++){ aux = 0; (i=0; i<12; i++) aux = aux ^ ( (y[j]&s)>>i & 0x01 ); q = (q<<1) ^ aux; } /******* step 5 */ //printf("step 5\n"); if (weight(q) <=3){ e[0] = 0; e[1] = q; }else{ /******* step 6 */ //printf("step 6\n"); = 0; found = 0; do{ if (weight(q^y[i]) <=2){ e[0] = x[i]; e[1] = q^y[i]; found = 1; } i++; }while((i<12) && (!found)); if ((i==12) && (!found)){ /******* step 7 */ printf("\n[e] - uncorrectable error pattern! (%3x | %3x)\n", r0, r1); /* can raise flag here, or output vector */ //exit(1); } } } } c_hat[0] = r0^e[0]; c_hat[1] = r1^e[1]; //printf("\t\testimated codeword = %x%x\n", c_hat[0], c_hat[1]); }
indeed, code little bit complex executed @ point of boot time. @ time there ne real crt , have minimal stack.
thus, moved code board_init_f() still part of spl. gave more stable results , algorithm works expected.
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