micropython · jepler · Jul 15, 2025 · Jul 15, 2025 · Jul 15, 2025 · Jul 15, 2025
diff --git a/.github/workflows/ports_unix.yml b/.github/workflows/ports_unix.yml
@@ -102,6 +102,20 @@ jobs:
       if: failure()
       run: tests/run-tests.py --print-failures
 
+  coverage_repr_b:
+    runs-on: ubuntu-22.04 # use 22.04 to get libffi-dev:i386
+    steps:
+    - uses: actions/checkout@v4
+    - name: Install packages
+      run: source tools/ci.sh && ci_unix_32bit_setup
+    - name: Build
+      run: source tools/ci.sh && ci_unix_coverage_repr_b_build
+    - name: Run main test suite
+      run: source tools/ci.sh && ci_unix_coverage_repr_b_run_tests
+    - name: Print failures
+      if: failure()
+      run: tests/run-tests.py --print-failures
+
   coverage_32bit:
     runs-on: ubuntu-22.04 # use 22.04 to get libffi-dev:i386
     steps:

diff --git a/extmod/moductypes.c b/extmod/moductypes.c
@@ -29,6 +29,7 @@
 #include <stdint.h>
 
 #include "py/runtime.h"
+#include "py/smallint.h"
 #include "py/objtuple.h"
 #include "py/binary.h"
 
@@ -43,14 +44,32 @@
 #define LAYOUT_BIG_ENDIAN    (1)
 #define LAYOUT_NATIVE        (2)
 
+#define LEN_BITS (OFFSET_BITS + BITF_OFF_BITS)
+#if MICROPY_OBJ_REPR == MICROPY_OBJ_REPR_B
+#define VAL_TYPE_BITS 4
+#define BITF_LEN_BITS 5
+#define BITF_OFF_BITS 5
+#define OFFSET_BITS 16
+#if VAL_TYPE_BITS + BITF_LEN_BITS + BITF_OFF_BITS + OFFSET_BITS != 30
+#error Invalid encoding field length
+#endif
+// Here we need to set sign bit right
+#define TYPE2SMALLINT(x, nbits) ((((int)x) << (32 - nbits)) >> 2)
+#define GET_TYPE(x, nbits) (((x) >> (30 - nbits)) & ((1 << nbits) - 1))
+#define VALUE_MASK(type_nbits) (~((int)0xc0000000 >> type_nbits))
+#else
 #define VAL_TYPE_BITS 4
 #define BITF_LEN_BITS 5
 #define BITF_OFF_BITS 5
 #define OFFSET_BITS 17
-#define LEN_BITS (OFFSET_BITS + BITF_OFF_BITS)
 #if VAL_TYPE_BITS + BITF_LEN_BITS + BITF_OFF_BITS + OFFSET_BITS != 31
 #error Invalid encoding field length
 #endif
+// Here we need to set sign bit right
+#define TYPE2SMALLINT(x, nbits) ((((mp_int_t)x) << (32 - nbits)) >> 1)
+#define GET_TYPE(x, nbits) (((x) >> (31 - nbits)) & ((1 << nbits) - 1))
+#define VALUE_MASK(type_nbits) (~((int)0x80000000 >> type_nbits))
+#endif
 
 enum {
     UINT8, INT8, UINT16, INT16,
@@ -68,12 +87,8 @@ enum {
     STRUCT, PTR, ARRAY,
 };
 
-// Here we need to set sign bit right
-#define TYPE2SMALLINT(x, nbits) ((((int)x) << (32 - nbits)) >> 1)
-#define GET_TYPE(x, nbits) (((x) >> (31 - nbits)) & ((1 << nbits) - 1))
 // Bit 0 is "is_signed"
 #define GET_SCALAR_SIZE(val_type) (1 << ((val_type) >> 1))
-#define VALUE_MASK(type_nbits) ~((int)0x80000000 >> type_nbits)
 
 #define IS_SCALAR_ARRAY(tuple_desc) ((tuple_desc)->len == 2)
 // We cannot apply the below to INT8, as their range [-128, 127]
@@ -94,6 +109,15 @@ static MP_NORETURN void syntax_error(void) {
 }
 
 static mp_obj_t uctypes_struct_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+    MP_STATIC_ASSERT(MP_SMALL_INT_FITS(TYPE2SMALLINT(BFINT32, VAL_TYPE_BITS)));
+    MP_STATIC_ASSERT(TYPE2SMALLINT(BFINT8, VAL_TYPE_BITS) != TYPE2SMALLINT(INT8, VAL_TYPE_BITS));
+    MP_STATIC_ASSERT(GET_TYPE(TYPE2SMALLINT(BFINT32, VAL_TYPE_BITS), VAL_TYPE_BITS) == BFINT32);
+    MP_STATIC_ASSERT(!(VALUE_MASK(VAL_TYPE_BITS) & TYPE2SMALLINT(BFINT32, VAL_TYPE_BITS)));
+    #if MICROPY_PY_BUILTINS_FLOAT
+    MP_STATIC_ASSERT(MP_SMALL_INT_FITS(TYPE2SMALLINT(FLOAT64, VAL_TYPE_BITS)));
+    MP_STATIC_ASSERT(GET_TYPE(TYPE2SMALLINT(FLOAT64, VAL_TYPE_BITS), VAL_TYPE_BITS) == FLOAT64);
+    MP_STATIC_ASSERT(!(VALUE_MASK(VAL_TYPE_BITS) & TYPE2SMALLINT(FLOAT64, VAL_TYPE_BITS)));
+    #endif
     mp_arg_check_num(n_args, n_kw, 2, 3, false);
     mp_obj_uctypes_struct_t *o = mp_obj_malloc(mp_obj_uctypes_struct_t, type);
     o->addr = (void *)(uintptr_t)mp_obj_get_int_truncated(args[0]);

diff --git a/py/objint.c b/py/objint.c
@@ -117,9 +117,15 @@ static mp_fp_as_int_class_t mp_classify_fp_as_int(mp_float_t val) {
     }
     // 8 * sizeof(uintptr_t) counts the number of bits for a small int
     // TODO provide a way to configure this properly
+    #if MICROPY_OBJ_REPR == MICROPY_OBJ_REPR_B
+    if (e <= ((8 * sizeof(uintptr_t) + MP_FLOAT_EXP_BIAS - 4) << MP_FLOAT_EXP_SHIFT_I32)) {
+        return MP_FP_CLASS_FIT_SMALLINT;
+    }
+    #else
     if (e <= ((8 * sizeof(uintptr_t) + MP_FLOAT_EXP_BIAS - 3) << MP_FLOAT_EXP_SHIFT_I32)) {
         return MP_FP_CLASS_FIT_SMALLINT;
     }
+    #endif
     #if MICROPY_LONGINT_IMPL == MICROPY_LONGINT_IMPL_LONGLONG
     if (e <= (((sizeof(long long) * MP_BITS_PER_BYTE) + MP_FLOAT_EXP_BIAS - 2) << MP_FLOAT_EXP_SHIFT_I32)) {
         return MP_FP_CLASS_FIT_LONGINT;

diff --git a/tests/basics/int_big_to_small.py b/tests/basics/int_big_to_small.py
@@ -5,6 +5,16 @@
     print("SKIP")
     raise SystemExit
 
+micropython.heap_lock()
+try:
+    k = (1 << 29)
+    k = k + 20
+except MemoryError:
+    micropython.heap_unlock()
+    print("SKIP")
+    raise SystemExit
+micropython.heap_unlock()
+
 # All less than small int max.
 for d in (0, 27, 1<<29, -1861, -(1<<29)):
     i = 1<<70

diff --git a/tests/basics/int_big_to_small_int29.py b/tests/basics/int_big_to_small_int29.py
@@ -0,0 +1,32 @@
+try:
+    import micropython
+    micropython.heap_lock
+except:
+    print("SKIP")
+    raise SystemExit
+
+micropython.heap_lock()
+try:
+    k = (1 << 28)
+    k = k + 20
+except MemoryError:
+    micropython.heap_unlock()
+    print("SKIP")
+    raise SystemExit
+micropython.heap_unlock()
+
+# All less than small int max.
+for d in (0, 27, 1<<28, -1861, -(1<<28)):
+    i = 1<<70
+    print(i)
+    j = (1<<70) + d
+    print(j)
+    # k should now be a small int.
+    k = j - i
+    print(k)
+
+    # Now verify that working with k doesn't allocate (i.e. it's a small int).
+    micropython.heap_lock()
+    print(k + 20)
+    print(k // 20)
+    micropython.heap_unlock()
diff --git a/tests/basics/int_big_to_small_int29.py.exp b/tests/basics/int_big_to_small_int29.py.exp
@@ -0,0 +1,25 @@
+1180591620717411303424
+1180591620717411303424
+0
+20
+0
+1180591620717411303424
+1180591620717411303451
+27
+47
+1
+1180591620717411303424
+1180591620717679738880
+268435456
+268435476
+13421772
+1180591620717411303424
+1180591620717411301563
+-1861
+-1841
+-94
+1180591620717411303424
+1180591620717142867968
+-268435456
+-268435436
+-13421773
diff --git a/tests/extmod/vfs_rom.py b/tests/extmod/vfs_rom.py
@@ -25,7 +25,7 @@
 # An mpy file with four constant objects: str, bytes, long-int, float.
 test_mpy = (
     # header
-    b"M\x06\x00\x1f"  # mpy file header
+    b"M\x06\x00\x1e"  # mpy file header
     b"\x06"  # n_qstr
     b"\x05"  # n_obj
     # qstrs

diff --git a/tests/micropython/import_mpy_native.py b/tests/micropython/import_mpy_native.py
@@ -53,11 +53,11 @@ def open(self, path, mode):
 
 
 # these are the test .mpy files
-valid_header = bytes([77, 6, mpy_arch, 31])
+valid_header = bytes([77, 6, mpy_arch, 30])
 # fmt: off
 user_files = {
     # bad architecture (mpy_arch needed for sub-version)
-    '/mod0.mpy': bytes([77, 6, 0xfc | mpy_arch, 31]),
+    '/mod0.mpy': bytes([77, 6, 0xfc | mpy_arch, 30]),
 
     # test loading of viper and asm
     '/mod1.mpy': valid_header + (

diff --git a/tests/perf_bench/core_import_mpy_multi.py b/tests/perf_bench/core_import_mpy_multi.py
@@ -23,7 +23,7 @@ def f():
     x = ("const tuple", None, False, True, 1, 2, 3)
 result = 123
 """
-file_data = b'M\x06\x00\x1f\x14\x03\x0etest.py\x00\x0f\x02A\x00\x02f\x00\x0cresult\x00/-5#\x82I\x81{\x81w\x82/\x81\x05\x81\x17Iom\x82\x13\x06arg\x00\x05\x1cthis will be a string object\x00\x06\x1bthis will be a bytes object\x00\n\x07\x05\x0bconst tuple\x00\x01\x02\x03\x07\x011\x07\x012\x07\x013\x81\\\x10\n\x01\x89\x07d`T2\x00\x10\x024\x02\x16\x022\x01\x16\x03"\x80{\x16\x04Qc\x02\x81d\x00\x08\x02(DD\x11\x05\x16\x06\x10\x02\x16\x072\x00\x16\x082\x01\x16\t2\x02\x16\nQc\x03`\x1a\x08\x08\x12\x13@\xb1\xb0\x18\x13Qc@\t\x08\t\x12` Qc@\t\x08\n\x12``Qc\x82@ \x0e\x03\x80\x08+)##\x12\x0b\x12\x0c\x12\r\x12\x0e*\x04Y\x12\x0f\x12\x10\x12\x11*\x03Y#\x00\xc0#\x01\xc0#\x02\xc0Qc'
+file_data = b'M\x06\x00\x1e\x14\x03\x0etest.py\x00\x0f\x02A\x00\x02f\x00\x0cresult\x00/-5#\x82I\x81{\x81w\x82/\x81\x05\x81\x17Iom\x82\x13\x06arg\x00\x05\x1cthis will be a string object\x00\x06\x1bthis will be a bytes object\x00\n\x07\x05\x0bconst tuple\x00\x01\x02\x03\x07\x011\x07\x012\x07\x013\x81\\\x10\n\x01\x89\x07d`T2\x00\x10\x024\x02\x16\x022\x01\x16\x03"\x80{\x16\x04Qc\x02\x81d\x00\x08\x02(DD\x11\x05\x16\x06\x10\x02\x16\x072\x00\x16\x082\x01\x16\t2\x02\x16\nQc\x03`\x1a\x08\x08\x12\x13@\xb1\xb0\x18\x13Qc@\t\x08\t\x12` Qc@\t\x08\n\x12``Qc\x82@ \x0e\x03\x80\x08+)##\x12\x0b\x12\x0c\x12\r\x12\x0e*\x04Y\x12\x0f\x12\x10\x12\x11*\x03Y#\x00\xc0#\x01\xc0#\x02\xc0Qc'
 
 
 class File(io.IOBase):

diff --git a/tests/perf_bench/core_import_mpy_single.py b/tests/perf_bench/core_import_mpy_single.py
@@ -78,7 +78,7 @@ def f1():
     x = ("const tuple 9", None, False, True, 1, 2, 3)
 result = 123
 """
-file_data = 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+file_data = 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 class File(io.IOBase):

diff --git a/tests/stress/fun_call_limit.py b/tests/stress/fun_call_limit.py
@@ -16,7 +16,7 @@ def test(n):
 
 
 # If the port has at least 32-bits then this test should pass.
-print(test(29))
+print(test(28))
 
 # This test should fail on all ports (overflows a small int).
 print(test(70))

diff --git a/tests/stress/fun_call_limit.py.exp b/tests/stress/fun_call_limit.py.exp
@@ -1,2 +1,2 @@
-33
+32
 SyntaxError
diff --git a/tools/ci.sh b/tools/ci.sh
@@ -522,6 +522,14 @@ CI_UNIX_OPTS_SANITIZE_UNDEFINED=(
     LDFLAGS_EXTRA="-fsanitize=undefined -fno-sanitize=nonnull-attribute"
 )
 
+CI_UNIX_OPTS_REPR_B=(
+    VARIANT=coverage
+    CFLAGS_EXTRA="-DMICROPY_OBJ_REPR=MICROPY_OBJ_REPR_B -Dmp_int_t=int32_t -Dmp_uint_t=uint32_t"
+    MICROPY_FORCE_32BIT=1
+    RUN_TESTS_MPY_CROSS_FLAGS="--mpy-cross-flags=\"-march=x86 -msmall-int-bits=29\""
+
+)
+
 function ci_unix_build_helper {
     make ${MAKEOPTS} -C mpy-cross
     make ${MAKEOPTS} -C ports/unix "$@" submodules
@@ -668,6 +676,15 @@ function ci_unix_32bit_setup {
     python3 --version
 }
 
+function ci_unix_coverage_repr_b_build {
+    ci_unix_build_helper "${CI_UNIX_OPTS_REPR_B[@]}"
+    ci_unix_build_ffi_lib_helper gcc -m32
+}
+
+function ci_unix_coverage_repr_b_run_tests {
+    ci_unix_run_tests_helper "${CI_UNIX_OPTS_REPR_B[@]}"
+}
+
 function ci_unix_coverage_32bit_build {
     ci_unix_build_helper VARIANT=coverage MICROPY_FORCE_32BIT=1
     ci_unix_build_ffi_lib_helper gcc -m32