py/objint.c: Code review of int_from_bytes().

Support signed param: result = int.int_from_bytes(bytearray(), order='big'|'little', signed=False|True) Signed-off-by: Ihor Nehrutsa <[email protected]>
IhorNehrutsa · Feb 22, 2025 · 1f0cf46 · 1f0cf46
1 parent 8987b39
commit 1f0cf46
Showing 1 changed file with 90 additions and 0 deletions.
diff --git a/py/objint.c b/py/objint.c
@@ -39,6 +39,8 @@
 #include <math.h>
 #endif
 
+#define debug_printf(...)  mp_printf(&mp_plat_print, __VA_ARGS__); mp_printf(&mp_plat_print, "\n"); // mp_printf(&mp_plat_print, " | func:%s line:%d at %s\n", __FUNCTION__, __LINE__, __FILE__);
+
 // This dispatcher function is expected to be independent of the implementation of long int
 static mp_obj_t mp_obj_int_make_new(const mp_obj_type_t *type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     (void)type_in;
@@ -387,6 +389,7 @@ mp_obj_t mp_obj_int_binary_op_extra_cases(mp_binary_op_t op, mp_obj_t lhs_in, mp
     return MP_OBJ_NULL; // op not supported
 }
 
+/*
 // this is a classmethod
 static mp_obj_t int_from_bytes(size_t n_args, const mp_obj_t *args) {
     // TODO: Support signed param (assumes signed=False at the moment)
@@ -416,6 +419,93 @@ static mp_obj_t int_from_bytes(size_t n_args, const mp_obj_t *args) {
     }
     return mp_obj_new_int_from_uint(value);
 }
+*/
+static void *reverce_memcpy(void *dest, const void *src, size_t len) {
+    char *d = (char *)dest + len - 1;
+    const char *s = src;
+    while (len--) {
+        *d-- = *s++;
+    }
+    return dest;
+}
+
+// this is a classmethod
+// result = int.int_from_bytes(bytearray(), order='big', signed=False)
+static mp_obj_t int_from_bytes(size_t n_args, const mp_obj_t *args) {
+    mp_buffer_info_t bufinfo;
+    mp_get_buffer_raise(args[1], &bufinfo, MP_BUFFER_READ);
+    const byte *buf = (const byte *)bufinfo.buf;
+    bool big_endian = (n_args < 3) || (args[2] != MP_OBJ_NEW_QSTR(MP_QSTR_little));
+    bool signd = (n_args > 3) && mp_obj_is_true(args[3]);
+
+    // debug_printf("mp_obj_is_bool(args[3])=%d", mp_obj_is_bool(args[3]));
+    // debug_printf("n_args=%d, MP_SMALL_INT_MAX=%d, MP_SMALL_INT_MIN=%d", n_args, MP_SMALL_INT_MAX, MP_SMALL_INT_MIN);
+    #if MICROPY_LONGINT_IMPL != MICROPY_LONGINT_IMPL_NONE
+    // if (((1U << (bufinfo.len * 8 - 2)) > (MP_SMALL_INT_MAX + 1)) || (big_endian ? buf[0] & 0x80 : buf[bufinfo.len - 1] & 0x80)) {
+    if ((1ULL << (bufinfo.len * 8 - 2)) > (MP_SMALL_INT_MAX + 1)) {
+        debug_printf("//1 Result will overflow a small-int so construct a big-int");
+        return mp_obj_int_from_bytes_impl(big_endian, bufinfo.len, bufinfo.buf);
+    }
+    #endif
+
+    union {
+        mp_int_t ival;
+        mp_uint_t uval;
+    } result;
+    if (big_endian) {
+        reverce_memcpy(&result.uval, buf, bufinfo.len);
+    } else {
+        memcpy(&result.uval, buf, bufinfo.len);
+    }
+    if (signd) {
+        #if MICROPY_LONGINT_IMPL != MICROPY_LONGINT_IMPL_NONE
+        debug_printf("big_endian:%d signed:%d bufinfo.len:%d sizeof(result.ival):%d result.ival:%ld", big_endian, signd, bufinfo.len, sizeof(result.ival), result.ival);
+        if ((result.ival > MP_SMALL_INT_MAX) || (result.ival < MP_SMALL_INT_MIN)) {
+            debug_printf("//2 Result will overflow a small-int so construct a big-int");
+            return mp_obj_int_from_bytes_impl(big_endian, bufinfo.len, bufinfo.buf);
+        }
+        #endif
+        return mp_obj_new_int(result.ival);
+    } else {
+        #if MICROPY_LONGINT_IMPL != MICROPY_LONGINT_IMPL_NONE
+        debug_printf("big_endian:%d signed:%d bufinfo.len:%d sizeof(result.uval):%d result.uval:%ld", big_endian, signd, bufinfo.len, sizeof(result.uval), result.uval);
+        if (result.uval > MP_SMALL_INT_MAX) {
+            debug_printf("//3 Result will overflow a small-int so construct a big-int");
+            return mp_obj_int_from_bytes_impl(big_endian, bufinfo.len, bufinfo.buf);
+        }
+        #endif
+        return mp_obj_new_int_from_uint(result.uval);
+    }
+/*
+    if (signd) {
+        mp_int_t result = 0;
+        if (big_endian) {
+            reverce_memcpy(&result, buf, bufinfo.len);
+        } else {
+            memcpy(&result, buf, bufinfo.len);
+        }
+        debug_printf("big_endian:%d signed:%d bufinfo.len:%d sizeof(result):%d result:%ld", big_endian, signd, bufinfo.len, sizeof(result), result);
+        if ((result > MP_SMALL_INT_MAX) || (result < MP_SMALL_INT_MIN)) {
+            debug_printf("// Result will overflow a small-int so construct a big-int");
+            return mp_obj_int_from_bytes_impl(big_endian, bufinfo.len, bufinfo.buf);
+        }
+        return mp_obj_new_int(result);
+    } else {
+        mp_uint_t result = 0;
+        if (big_endian) {
+            reverce_memcpy(&result, buf, bufinfo.len);
+        } else {
+            memcpy(&result, buf, bufinfo.len);
+        }
+        debug_printf("big_endian:%d unsigned:%d bufinfo.len:%d sizeof(result):%d result:%ld", big_endian, signd, bufinfo.len, sizeof(result), result);
+        if ((result > MP_SMALL_INT_MAX) || (result < MP_SMALL_INT_MIN)) {
+            debug_printf("// Result will overflow a small-int so construct a big-int");
+            return mp_obj_int_from_bytes_impl(big_endian, bufinfo.len, bufinfo.buf);
+        }
+        return mp_obj_new_int_from_uint(result);
+    }
+*/
+}
 
 static MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(int_from_bytes_fun_obj, 2, 4, int_from_bytes);
 static MP_DEFINE_CONST_CLASSMETHOD_OBJ(int_from_bytes_obj, MP_ROM_PTR(&int_from_bytes_fun_obj));