From b8cfb0d7b2c91ea1e17f6caeabfc9cb23166cdc1 Mon Sep 17 00:00:00 2001
From: Damien George
Date: Fri, 27 Nov 2015 17:09:11 +0000
Subject: 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.
---
 py/mpconfig.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

(limited to 'py/mpconfig.h')

diff --git a/py/mpconfig.h b/py/mpconfig.h
index 01956f63f..1f01b3de5 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
-- 
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