unix/modtime: Implement ticks_ms(), ticks_us() and ticks_diff().

All of these functions return positive small int, thus range is 2 bits less
than word size (30 bit on 32-bit systems, 62 bit on 64-bit systems).

py/smallint.h

@@ -36,11 +36,15 @@
 
 #define MP_SMALL_INT_MIN ((mp_int_t)(((mp_int_t)WORD_MSBIT_HIGH) >> 1))
 #define MP_SMALL_INT_FITS(n) ((((n) ^ ((n) << 1)) & WORD_MSBIT_HIGH) == 0)
+// Mask to truncate mp_int_t to positive value
+#define MP_SMALL_INT_POSITIVE_MASK ~(WORD_MSBIT_HIGH | (WORD_MSBIT_HIGH >> 1))
 
 #elif MICROPY_OBJ_REPR == MICROPY_OBJ_REPR_B
 
 #define MP_SMALL_INT_MIN ((mp_int_t)(((mp_int_t)WORD_MSBIT_HIGH) >> 2))
 #define MP_SMALL_INT_FITS(n) ((((n) & MP_SMALL_INT_MIN) == 0) || (((n) & MP_SMALL_INT_MIN) == MP_SMALL_INT_MIN))
+// Mask to truncate mp_int_t to positive value
+#define MP_SMALL_INT_POSITIVE_MASK ~(WORD_MSBIT_HIGH | (WORD_MSBIT_HIGH >> 1) | (WORD_MSBIT_HIGH >> 2))
 
 #endif
 

unix/modtime.c

@@ -31,6 +31,7 @@
 #include <math.h>
 
 #include "py/runtime.h"
+#include "py/smallint.h"
 
 #ifdef _WIN32
 void msec_sleep_tv(struct timeval *tv) {
@@ -69,6 +70,29 @@ STATIC mp_obj_t mod_time_time(void) {
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_0(mod_time_time_obj, mod_time_time);
 
+STATIC mp_obj_t mod_time_ticks_us(void) {
+    struct timeval tv;
+    gettimeofday(&tv, NULL);
+    mp_uint_t us = tv.tv_sec * 1000000 + tv.tv_usec;
+    return MP_OBJ_NEW_SMALL_INT(us & MP_SMALL_INT_POSITIVE_MASK);
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_0(mod_time_ticks_us_obj, mod_time_ticks_us);
+
+STATIC mp_obj_t mod_time_ticks_ms(void) {
+    struct timeval tv;
+    gettimeofday(&tv, NULL);
+    mp_uint_t ms = tv.tv_sec * 1000 + tv.tv_usec / 1000;
+    return MP_OBJ_NEW_SMALL_INT(ms & MP_SMALL_INT_POSITIVE_MASK);
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_0(mod_time_ticks_ms_obj, mod_time_ticks_ms);
+
+STATIC mp_obj_t mod_time_ticks_diff(mp_obj_t oldval, mp_obj_t newval) {
+    mp_uint_t old = MP_OBJ_SMALL_INT_VALUE(oldval);
+    mp_uint_t new = MP_OBJ_SMALL_INT_VALUE(newval);
+    return MP_OBJ_NEW_SMALL_INT((new - old) & MP_SMALL_INT_POSITIVE_MASK);
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_time_ticks_diff_obj, mod_time_ticks_diff);
+
 // Note: this is deprecated since CPy3.3, but pystone still uses it.
 STATIC mp_obj_t mod_time_clock(void) {
 #if MICROPY_PY_BUILTINS_FLOAT
@@ -116,6 +140,9 @@ STATIC const mp_map_elem_t mp_module_time_globals_table[] = {
     { MP_OBJ_NEW_QSTR(MP_QSTR_sleep_ms), (mp_obj_t)&mod_time_sleep_ms_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_sleep_us), (mp_obj_t)&mod_time_sleep_us_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_time), (mp_obj_t)&mod_time_time_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_ticks_ms), (mp_obj_t)&mod_time_ticks_ms_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_ticks_us), (mp_obj_t)&mod_time_ticks_us_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_ticks_diff), (mp_obj_t)&mod_time_ticks_diff_obj },
 };
 
 STATIC MP_DEFINE_CONST_DICT(mp_module_time_globals, mp_module_time_globals_table);

unix/qstrdefsport.h

@@ -62,6 +62,9 @@ Q(clock)
 Q(sleep)
 Q(sleep_ms)
 Q(sleep_us)
+Q(ticks_ms)
+Q(ticks_us)
+Q(ticks_diff)
 
 Q(socket)
 Q(sockaddr_in)