Page 244 - ARM 64 Bit Assembly Language

232 Chapter 7

159 clock_t test_division(int size, bigint l[], bigint r[], bigint op[]) {
160 char *name = "Div";
161 bigint d, labs, rabs;
162 clock_t stop, start = clock();
163 for (int i = 0; i < size; i++) {
164 /* Use largest absolute value for dividend and smaller absoulute
165 * value as divisor */
166 labs = bigint_abs(l[i]);
167 rabs = bigint_abs(r[i]);
168 if (bigint_gt(labs, rabs)) {
169 d = bigint_div(l[i], r[i]);
170 if (bigint_ne(d, op[i]))
171 matherr(l[i], r[i], op[i], d, name);
172 } else {
173 d = bigint_div(r[i], l[i]);
174 if (bigint_ne(d, op[i]))
175 matherr(r[i], l[i], op[i], d, name);
176 }
177 bigint_free(labs);
178 bigint_free(rabs);
179 bigint_free(d);
180 }
181 stop = clock();
182 printf("%s :\t %lf\n", name, (stop - start)/(double)CLOCKS_PER_SEC);
183 return (stop - start);
184 }
185
186 clock_t test_sqrt(int size, bigint l[], bigint op[]) {
187 char *name = "Sqrt";
188 bigint d, abs;
189 clock_t stop, start = clock();
190 for (int i = 0; i < size; i++) {
191 abs = bigint_abs(l[i]);
192 d = bigint_sqrt(abs);
193 if (bigint_ne(d, op[i]))
194 sqrterr(abs, op[i], d, name);
195 bigint_free(abs);
196 bigint_free(d);
197 }
198 stop = clock();
199 printf("%s :\t %lf\n", name, (stop - start)/(double)CLOCKS_PER_SEC);
200 return (stop - start);
201 }

The implementation could be made more efficient by writing some of the functions in assem-
bly language. One opportunity for improvement is in the add function, which must calculate
the carry from one chunk of bits to the next. In assembly, the programmer has direct access to
the carry bit, so carry propagation should be much faster.