Assembly and C programs to count number of negative 8-bit numbers from 0xE000 to 0xEFFF

Assemble language program

; Program to count negative 8-bit numbers
; from 0xE000 to 0xEFFF
; Bill Rison
; 2/15/98


         .title  COUNT NEG NUMBERS

EVBRAM   =  0x0000              ;0x0000 is start of user ram on 68HC11EVBU
DATA     =  EVBRAM
PROG     =  EVBRAM+0x100        ;start program above BUFFALO
START    =  0xE000              ;start of table
END      =  0xEFFF              ;end of table

         .area   CODE  (ABS)

         .org    PROG           ;set program counter to 0x0100
start:   ldx     #START         ;Reg X points to entry to process 
         ldy     #0             ;Hold sum in Y -- clear to start
l1:      brset   0,x,#0x80,l2   ;If entry is positive (MSB=0), don't sum
         iny                    ;Add to count in Y
l2:      inx                    ;REG X points to next entry in table1
         cpx     #END           ;Has pointer gone past end of table?
         bls     l1             ;If not done, process next table entry
         sty     count          ;Save result
         swi                    ;Done -- Exit



         .area   DATA  (ABS)

         .org    DATA
count:   .ds     2

C language program using do {} while (); form

/*
 * Program to count the number of 
 * 8-bit negative numbers from
 * 0xE000 to 0xEFFF
 *
 * February 5, 1998  Bill Rison
 */

#define START 0xE000
#define END   0xEFFF

main()
{
    int count;
    char *ptr;

    count = 0;
    ptr = START;
    do
    {
        if (*ptr < 0)
        {
            count = count + 1;
        }
        ptr = ptr + 1;
    }
    while (ptr <= END);
}

C language program using while () { } form

/*
 * Program to count the number of 
 * 8-bit negative numbers from
 * 0xE000 to 0xEFFF
 *
 * February 5, 1998  Bill Rison
 */

#define START 0xE000
#define END   0xEFFF

main()
{
    int count;
    char *ptr;

    count = 0;
    ptr = START;
    while (ptr <= END)
    {
        if (*ptr < 0)
        {
            count = count + 1;
        }
        ptr = ptr + 1;
    }
}