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[/] [openrisc/] [trunk/] [orpsocv2/] [sw/] [tests/] [or1200/] [sim/] [or1200-div.c] - Rev 466
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/* Test integer division Use a software division algorithm to perform division and compare against the hardware calculated results TODO: Check the signed division software calculation stuff is 100% correct! Julius Baxter, julius@opencores.org */ #include "cpu-utils.h" #include "printf.h" static int sdiv_errors, udiv_errors; #define VERBOSE_TESTS 0 // Make this bigger when running on FPGA target. For simulation it's enough. #define NUM_TESTS 2000 int or1k_div(int dividend, int divisor) { int result; asm ("l.div\t%0,%1,%2" : "=r" (result) : "r" (dividend), "r" (divisor)); return result; } unsigned int or1k_divu(unsigned int dividend, unsigned int divisor) { int result; asm ("l.divu\t%0,%1,%2" : "=r" (result) : "r" (dividend), "r" (divisor)); return result; } void check_div(int dividend, int divisor, int expected_result) { #if VERBOSE_TESTS printf("l.div 0x%.8x / 0x%.8x = (SW) 0x%.8x : ", dividend, divisor, expected_result); #endif int result = or1k_div(dividend, divisor); report(result); if ( result != expected_result) { printf("l.div 0x%.8x / 0x%.8x = (SW) 0x%.8x : ", dividend, divisor, expected_result); printf("(HW) 0x%.8x - MISMATCH\n",result); sdiv_errors++; } #if VERBOSE_TESTS else printf("OK\n"); #endif } void check_divu(unsigned int dividend, unsigned int divisor, unsigned int expected_result) { #if VERBOSE_TESTS printf("l.divu 0x%.8x / 0x%.8x = (SW) 0x%.8x : ", dividend, divisor, expected_result); #endif unsigned int result = or1k_divu(dividend, divisor); report(result); if ( result != expected_result) { printf("l.divu 0x%.8x / 0x%.8x = (SW) 0x%.8x : ", dividend, divisor, expected_result); printf("(HW) 0x%.8x - MISMATCH\n",result); udiv_errors++; } #if VERBOSE_TESTS else printf("OK\n"); #endif } // Software implementation of division unsigned int div_soft(unsigned int n, unsigned int d) { // unsigned 32-bit restoring divide algo: unsigned long long p, dd; long long p_signed; unsigned int q = 0; p = (unsigned long long) n; dd = (unsigned long long) d << 32; int i; for(i=31; i>-1; i--){ p_signed = (2*p) - dd; if (p_signed>=0) { p = (2*p) - dd; q |= 1 << i; } else { p = p_signed + dd; } } return q; } int main(void) { #ifdef _UART_H_ uart_init(DEFAULT_UART); #endif udiv_errors = 0; sdiv_errors = 0; int i; unsigned long n, d; unsigned long expected_result; i=0; while(i < NUM_TESTS) { n = rand(); d = rand(); report(0x10101010); while ( d >= n ) d >>= (rand() & 0xff); if (n&0x80000000) // numerator is negative { // Calculate a value that's really smaller than the numerator while ( d >= ~(n-1) ) d >>= (rand() & 0xff); if (!d) d = 1; // Processor thinks it's in 2's complement already, so we'll convert // from the interpreted 2's complement to unsigned for our calculation expected_result = div_soft(~(n-1), d); // Answer will be an unsigned +ve value, but of course it has to be // negative so convert back to 2's complment negative expected_result = ~expected_result + 1; // 2's complement } else expected_result = div_soft(n, d); /* Report things */ report(n); report(d); report(expected_result); /* Signed divide */ check_div(n, d, expected_result); /* Unsigned divide test */ /* Ensure numerator's bit 31 is clear */ n >>= 1; /* If divisor is > numerator, shift it by a random amount */ while ( d >= n ) d >>= (rand() & 0xff); if (!d) d = 1; expected_result = div_soft(n, d); /* Report things */ report(n); report(d); report(expected_result); /* Unsigned divide */ check_divu(n, d, expected_result); i++; } printf("Division check complete\n"); printf("Unsigned:\t%d tests\t %d errors\n", NUM_TESTS, udiv_errors); printf("Signed:\t\t%d tests\t %d errors\n", NUM_TESTS, sdiv_errors); if ((udiv_errors > 0) || (sdiv_errors > 0)) report(0xbaaaaaad); else report(0x8000000d); return 0; }
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