Merge pull request #312 from pfalcon/int-varlen

Support varlen encoding for arbitrary int and uint numbers

1 files changed, 23 insertions, 6 deletions

diff --git a/py/vm.c b/py/vm.c
index 573167b57d..cab340ff38 100644
--- a/py/vm.c
+++ b/py/vm.c
@@ -38,10 +38,20 @@ typedef enum {
     UNWIND_JUMP,
 } mp_unwind_reason_t;
 
-#define DECODE_UINT do { unum = *ip++; if (unum > 127) { unum = ((unum & 0x3f) << 8) | (*ip++); } } while (0)
+#define DECODE_UINT { \
+    unum = 0; \
+    do { \
+        unum = (unum << 7) + (*ip & 0x7f); \
+    } while ((*ip++ & 0x80) != 0); \
+}
 #define DECODE_ULABEL do { unum = (ip[0] | (ip[1] << 8)); ip += 2; } while (0)
 #define DECODE_SLABEL do { unum = (ip[0] | (ip[1] << 8)) - 0x8000; ip += 2; } while (0)
-#define DECODE_QSTR do { qst = *ip++; if (qst > 127) { qst = ((qst & 0x3f) << 8) | (*ip++); } } while (0)
+#define DECODE_QSTR { \
+    qst = 0; \
+    do { \
+        qst = (qst << 7) + (*ip & 0x7f); \
+    } while ((*ip++ & 0x80) != 0); \
+}
 #define PUSH(val) *++sp = (val)
 #define POP() (*sp--)
 #define TOP() (*sp)
@@ -146,11 +156,18 @@ dispatch_loop:
                         PUSH(mp_const_ellipsis);
                         break;
 
-                    case MP_BC_LOAD_CONST_SMALL_INT:
-                        unum = (ip[0] | (ip[1] << 8) | (ip[2] << 16)) - 0x800000;
-                        ip += 3;
-                        PUSH(MP_OBJ_NEW_SMALL_INT(unum));
+                    case MP_BC_LOAD_CONST_SMALL_INT: {
+                        int num = 0;
+                        if ((ip[0] & 0x40) != 0) {
+                            // Number is negative
+                            num--;
+                        }
+                        do {
+                            num = (num << 7) | (*ip & 0x7f);
+                        } while ((*ip++ & 0x80) != 0);
+                        PUSH(MP_OBJ_NEW_SMALL_INT(num));
                         break;
+                    }
 
                     case MP_BC_LOAD_CONST_INT:
                         DECODE_QSTR;