not very idiomatic haskell code

gistfile1.txt

#include "Cmm.h"

#define W_TO_SHORT(x) %lobits32(x)


crc16u {
    /* R1 uint32_t input, 
       R2 uint16_t data, 
       R3 Int size */
    I32 c;
    if (R3 == 0) goto end;
    c = R1;
    R4 = 0;
    loop:
//    R1 = (R1 + TO_W_(bits16[R2+R4]) % 0xFFFF) % 0xFFFFFFFF;
//    R4 = R4 + 2;
//    R1 = HALF_W_(HALF_W_(R1) + HALF_W_(bits32[R2+R4]));
    c  = c + W_TO_SHORT(bits16[R2+R4]);
    R4 = R4 + 2;
    if (R4<R3) goto loop;
    if (R4>R3) {
        c = c + W_TO_SHORT(bits8[R2+R3] << 8);
    }
    R1 = TO_W_(c);
    end:
    jump %ENTRY_CODE(Sp(0));
}

#if 0
crc16(uint32_t w,uint16_t *b,size_t l) {
    while (l--) {
        w += b;
    }
    return w;
}
#endif