//----------------------------------------------------------------
//	divtest.cpp
//
//	This program uses "inline assembly language" to test our
//	external 'softdivb' software division function, based on
//	comparing all its possible outputs with results produced
//	when the same divisions are performed in hardware.  Note 
//	that only those cases in which a "divide overlow" cannot
//	occur are tested here.  
//
//	compile using:  $ g++ divtest.cpp div_bl.o -o divtest
//
//	programmer: ALLAN CRUSE
//	written on: 12 OCT 2003
//	revised on: 22 FEB 2005
//----------------------------------------------------------------

#include <stdio.h>		// needed for printf()

extern void softdivb( void );	// function symbol

unsigned int	a, b, c, d;	// global variables

int main( void )
{
	printf( "\n---a--- --b--  hardware  software \n" );
	
	// iterate over all possible combinations 
	// of 16-bit dividend and 8-bit divisor 
	int	errors = 0;
	for (a = 0; a < 65536; a++)
		{
		for (b = 0; b < 256; b++)
			{
			printf( " a=%04X  b=%02X ", a, b );
			if ( ( a >> 8 ) < b )
				{	
				asm(" movw a, %ax ");
			       	asm(" movb b, %bl ");
				asm(" divb %bl ");
				asm(" movw %ax, d ");
				asm(" movw a, %ax ");
			       	asm(" movb b, %bl ");
				asm(" call softdivb ");
				asm(" movw %ax, c ");
				printf( "  c=%04X    d=%04X ", c, d );
				if ( c != d ) ++errors;
				if ( c == d ) printf( "     ok \n" );
				else	printf( "<--- error #%d \n", errors );
				}
			else	printf( "  (divide overflow)  \n" );
			}
		}
	
	printf( "\n\tNumber of errors = %d \n\n", errors );
}