NAME

       benchmarks - Benchmarks The results below can only give a rough estimate of the resources
       necessary for using certain library functions. There is a number of factors which can both
       increase or reduce the effort required:

       • Expenses for preparation of operands and their stack are not considered.
       • In the table, the size includes all additional functions (for example, function to
         multiply two integers) but they are only linked from the library.
       • Expenses of time of performance of some functions essentially depend on parameters of a
         call, for example, qsort() is recursive, and sprintf() receives parameters in a stack.
       • Different versions of the compiler can give a significant difference in code size and
         execution time. For example, the dtostre() function, compiled with avr-gcc 3.4.6,
         requires 930 bytes. After transition to avr-gcc 4.2.3, the size become 1088 bytes.

A few of libc functions.

       Avr-gcc version is 4.7.1
       The size of function is given in view of all picked up functions. By default Avr-libc is
       compiled with -mcall-prologues option. In brackets the size without taking into account
       modules of a prologue and an epilogue is resulted. Both of the size can coincide, if
       function does not cause a prologue/epilogue.
        Function Units Avr2 Avr25 Avr4  atoi ('12345') Flash bytes
       Stack bytes
       MCU clocks 82 (82)
       2
       155 78 (78)
       2
       149 74 (74)
       2
       149  atol ('12345') Flash bytes
       Stack bytes
       MCU clocks 122 (122)
       2
       221 118 (118)
       2
       219 118 (118)
       2
       219  dtostre (1.2345, s, 6, 0) Flash bytes
       Stack bytes
       MCU clocks 1116 (1004)
       17
       1247 1048 (938)
       17
       1105 1048 (938)
       17
       1105  dtostrf (1.2345, 15, 6, s) Flash bytes
       Stack bytes
       MCU clocks 1616 (1616)
       38
       1634 1508 (1508)
       38
       1462 1508 (1508)
       38
       1462  itoa (12345, s, 10) Flash bytes
       Stack bytes
       MCU clocks 110 (110)
       2
       879 102 (102)
       2
       875 102 (102)
       2
       875  ltoa (12345L, s, 10) Flash bytes
       Stack bytes
       MCU clocks 134 (134)
       2
       1597 126 (126)
       2
       1593 126 (126)
       2
       1593  malloc (1) Flash bytes
       Stack bytes
       MCU clocks 768 (712)
       6
       215 714 (660)
       6
       201 714 (660)
       6
       201  realloc ((void *)0, 1) Flash bytes
       Stack bytes
       MCU clocks 1284 (1172)
       18
       305 1174 (1064)
       18
       286 1174 (1064)
       18
       286  qsort (s, sizeof(s), 1, cmp) Flash bytes
       Stack bytes
       MCU clocks 1252 (1140)
       42
       21996 1022 (912)
       42
       19905 1028 (918)
       42
       17541  sprintf_min (s, '%d', 12345) Flash bytes
       Stack bytes
       MCU clocks 1224 (1112)
       53
       1841 1092 (982)
       53
       1694 1088 (978)
       53
       1689  sprintf (s, '%d', 12345) Flash bytes
       Stack bytes
       MCU clocks 1614 (1502)
       58
       1647 1476 (1366)
       58
       1552 1454 (1344)
       58
       1547  sprintf_flt (s, '%e', 1.2345) Flash bytes
       Stack bytes
       MCU clocks 3228 (3116)
       67
       2573 2990 (2880)
       67
       2311 2968 (2858)
       67
       2311  sscanf_min ('12345', '%d', &i) Flash bytes
       Stack bytes
       MCU clocks 1532 (1420)
       55
       1607 1328 (1218)
       55
       1446 1328 (1218)
       55
       1446  sscanf ('12345', '%d', &i) Flash bytes
       Stack bytes
       MCU clocks 2008 (1896)
       55
       1610 1748 (1638)
       55
       1449 1748 (1638)
       55
       1449  sscanf ('point,color', '%[a-z]', s) Flash bytes
       Stack bytes
       MCU clocks 2008 (1896)
       86
       3067 1748 (1638)
       86
       2806 1748 (1638)
       86
       2806  sscanf_flt ('1.2345', '%e', &x) Flash bytes
       Stack bytes
       MCU clocks 3464 (3352)
       71
       2497 3086 (2976)
       71
       2281 3070 (2960)
       71
       2078  strtod ('1.2345', &p) Flash bytes
       Stack bytes
       MCU clocks 1632 (1520)
       20
       1235 1536 (1426)
       20
       1177 1480 (1480)
       21
       1124  strtol ('12345', &p, 0) Flash bytes
       Stack bytes
       MCU clocks 918 (806)
       22
       956 834 (724)
       22
       891 792 (792)
       28
       794

Math functions.

       The table contains the number of MCU clocks to calculate a function with a given
       argument(s). The main reason of a big difference between Avr2 and Avr4 is a hardware
       multiplication.
       Function Avr2 Avr4  __addsf3 (1.234, 5.678) 113 108  __mulsf3 (1.234, 5.678) 375 138
       __divsf3 (1.234, 5.678) 466 465  acos (0.54321) 4411 2455  asin (0.54321) 4517 2556  atan
       (0.54321) 4710 2271  atan2 (1.234, 5.678) 5270 2857  cbrt (1.2345) 2684 2555  ceil
       (1.2345) 177 177  cos (1.2345) 3387 1671  cosh (1.2345) 4922 2979  exp (1.2345) 4708 2765
       fdim (5.678, 1.234) 111 111  floor (1.2345) 180 180  fmax (1.234, 5.678) 39 37  fmin
       (1.234, 5.678) 35 35  fmod (5.678, 1.234) 131 131  frexp (1.2345, 0) 42 41  hypot (1.234,
       5.678) 1341 866  ldexp (1.2345, 6) 42 42  log (1.2345) 4142 2134  log10 (1.2345) 4498 2260
       modf (1.2345, 0) 433 429  pow (1.234, 5.678) 9293 5047  round (1.2345) 150 150  sin
       (1.2345) 3353 1653  sinh (1.2345) 4946 3003  sqrt (1.2345) 494 492  tan (1.2345) 4381 2426
       tanh (1.2345) 5126 3173  trunc (1.2345) 178 178