py: Add support for 64-bit NaN-boxing object model, on 32-bit machine.
To use, put the following in mpconfigport.h:
#define MICROPY_OBJ_REPR (MICROPY_OBJ_REPR_D)
#define MICROPY_FLOAT_IMPL (MICROPY_FLOAT_IMPL_DOUBLE)
typedef int64_t mp_int_t;
typedef uint64_t mp_uint_t;
#define UINT_FMT "%llu"
#define INT_FMT "%lld"
Currently does not work with native emitter enabled.
diff --git a/py/mpconfig.h b/py/mpconfig.h
index 01956f6..1f01b3d 100644
--- a/py/mpconfig.h
+++ b/py/mpconfig.h
@@ -76,6 +76,19 @@
#define MICROPY_OBJ_REPR_C (2)
+// A MicroPython object is a 64-bit word having the following form (called R):
+// - seeeeeee eeeeffff ffffffff ffffffff ffffffff ffffffff ffffffff ffffffff 64-bit fp, e != 0x7ff
+// - s1111111 11110000 00000000 00000000 00000000 00000000 00000000 00000000 +/- inf
+// - 01111111 11111000 00000000 00000000 00000000 00000000 00000000 00000000 normalised nan
+// - 01111111 11111101 00000000 00000000 iiiiiiii iiiiiiii iiiiiiii iiiiiii1 small int
+// - 01111111 11111110 00000000 00000000 qqqqqqqq qqqqqqqq qqqqqqqq qqqqqqq1 str
+// - 01111111 11111100 00000000 00000000 pppppppp pppppppp pppppppp pppppp00 ptr (4 byte alignment)
+// Stored as O = R + 0x8004000000000000, retrieved as R = O - 0x8004000000000000.
+// This makes pointers have all zeros in the top 32 bits.
+// Small-ints and strs have 1 as LSB to make sure they don't look like pointers
+// to the garbage collector.
+#define MICROPY_OBJ_REPR_D (3)
+
#ifndef MICROPY_OBJ_REPR
#define MICROPY_OBJ_REPR (MICROPY_OBJ_REPR_A)
#endif