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Commit 7d71178

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committed
Implement getstatic and putstatic
Add a new test script: "Static.java"
1 parent 0d95b5c commit 7d71178

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6 files changed

+171
-3
lines changed

6 files changed

+171
-3
lines changed

‎Makefile‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -46,7 +46,8 @@ TESTS = \
4646
Long \
4747
Caller \
4848
Constructor \
49-
Field
49+
Field \
50+
Static
5051

5152
check: $(addprefix tests/,$(TESTS:=-result.out))
5253

‎class-heap.c‎

Lines changed: 5 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -91,6 +91,11 @@ void free_class_heap()
9191
free(constant->info);
9292
}
9393
free(class_heap.class_info[i]->clazz->constant_pool.constant_pool);
94+
95+
field_t *field = class_heap.class_info[i]->clazz->fields;
96+
for (u2 j = 0; j < class_heap.class_info[i]->clazz->fields_count;
97+
j++, field++)
98+
free(field->static_var);
9499
free(class_heap.class_info[i]->clazz->fields);
95100

96101
for (method_t *method = class_heap.class_info[i]->clazz->methods;

‎classfile.c‎

Lines changed: 22 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -31,6 +31,27 @@ uint16_t get_number_of_parameters(method_t *method)
3131
return strlen(method->descriptor) - 3;
3232
}
3333

34+
/**
35+
* Find the field with the given name and signature.
36+
* The difference between `find_field` and `object_heap:find_field_addr`
37+
* is that `find_field` is used to find class level field (i.e. static field),
38+
* and `find_field_addr` is used to find object level field.
39+
*
40+
* @param name the field name
41+
* @param desc the field descriptor string, e.g. "(I)I"
42+
* @param clazz the parsed class file
43+
* @return the field if it was found, or NULL
44+
*/
45+
field_t *find_field(const char *name, const char *desc, class_file_t *clazz)
46+
{
47+
field_t *field = clazz->fields;
48+
for (u2 i = 0; i < clazz->fields_count; ++i, field++) {
49+
if (!(strcmp(name, field->name) || strcmp(desc, field->descriptor)))
50+
return field;
51+
}
52+
return NULL;
53+
}
54+
3455
/**
3556
* Find the method with the given name and signature.
3657
* The descriptor is necessary because Java allows method overloading.
@@ -218,6 +239,7 @@ field_t *get_fields(FILE *class_file, constant_pool_t *cp, class_file_t *clazz)
218239
const_pool_info *descriptor = get_constant(cp, info.descriptor_index);
219240
assert(descriptor->tag == CONSTANT_Utf8 && "Expected a UTF8");
220241
field->descriptor = (char *) descriptor->info;
242+
field->static_var = malloc(sizeof(variable_t));
221243

222244
read_field_attributes(class_file, &info);
223245
}

‎classfile.h‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -51,6 +51,7 @@ typedef struct {
5151
char *class_name;
5252
char *name;
5353
char *descriptor;
54+
variable_t *static_var; /* store static fields in the class */
5455
} field_t;
5556

5657
typedef struct {
@@ -73,6 +74,7 @@ void read_method_attributes(FILE *class_file,
7374
code_t *code,
7475
constant_pool_t *cp);
7576
uint16_t get_number_of_parameters(method_t *method);
77+
field_t *find_field(const char *name, const char *desc, class_file_t *clazz);
7678
method_t *find_method(const char *name, const char *desc, class_file_t *clazz);
7779
method_t *find_method_from_index(uint16_t idx, class_file_t *clazz);
7880
class_file_t get_class(FILE *class_file);

‎jvm.c‎

Lines changed: 117 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -94,6 +94,7 @@ typedef enum {
9494
i_areturn = 0xb0,
9595
i_return = 0xb1,
9696
i_getstatic = 0xb2,
97+
i_putstatic = 0xb3,
9798
i_getfield = 0xb4,
9899
i_putfield = 0xb5,
99100
i_invokevirtual = 0xb6,
@@ -785,10 +786,124 @@ stack_entry_t *execute(method_t *method,
785786
break;
786787

787788
/* Get static field from class */
788-
case i_getstatic:
789-
/* FIXME: unimplemented */
789+
case i_getstatic: {
790+
uint8_t param1 = code_buf[pc + 1], param2 = code_buf[pc + 2];
791+
uint16_t index = ((param1 << 8) | param2);
792+
793+
char *field_name, *field_descriptor, *class_name;
794+
class_name = find_field_info_from_index(index, clazz, &field_name,
795+
&field_descriptor);
796+
797+
/* skip java.lang.System in order to support java print
798+
* method */
799+
if (!strcmp(class_name, "java/lang/System")) {
800+
pc += 3;
801+
break;
802+
}
803+
804+
class_file_t *target_class =
805+
find_or_add_class_to_heap(class_name, prefix);
806+
field_t *field =
807+
find_field(field_name, field_descriptor, target_class);
808+
809+
switch (field_descriptor[0]) {
810+
case 'B':
811+
/* signed byte */
812+
push_byte(op_stack, field->static_var->value.char_value);
813+
break;
814+
case 'C':
815+
/* FIXME: complete Unicode handling */
816+
/* unicode character code */
817+
push_short(op_stack, field->static_var->value.short_value);
818+
break;
819+
case 'I':
820+
/* integer */
821+
push_int(op_stack, field->static_var->value.int_value);
822+
break;
823+
case 'J':
824+
/* long integer */
825+
push_long(op_stack, field->static_var->value.long_value);
826+
break;
827+
case 'S':
828+
/* signed short */
829+
push_short(op_stack, field->static_var->value.short_value);
830+
break;
831+
case 'Z':
832+
/* true or false */
833+
push_byte(op_stack, field->static_var->value.char_value);
834+
break;
835+
case 'L':
836+
/* an instance of class */
837+
push_ref(op_stack, field->static_var->value.ptr_value);
838+
break;
839+
default:
840+
fprintf(stderr, "Unknown field descriptor %c\n",
841+
field_descriptor[0]);
842+
exit(1);
843+
}
790844
pc += 3;
791845
break;
846+
}
847+
848+
/* Put static field to class */
849+
case i_putstatic: {
850+
uint8_t param1 = code_buf[pc + 1], param2 = code_buf[pc + 2];
851+
uint16_t index = ((param1 << 8) | param2);
852+
853+
char *field_name, *field_descriptor, *class_name;
854+
class_name = find_field_info_from_index(index, clazz, &field_name,
855+
&field_descriptor);
856+
857+
class_file_t *target_class =
858+
find_or_add_class_to_heap(class_name, prefix);
859+
field_t *field =
860+
find_field(field_name, field_descriptor, target_class);
861+
862+
switch (field_descriptor[0]) {
863+
case 'B':
864+
/* signed byte */
865+
field->static_var->value.char_value = (u1) pop_int(op_stack);
866+
field->static_var->type = VAR_BYTE;
867+
break;
868+
case 'C':
869+
/* FIXME: complete Unicode handling */
870+
/* unicode character code */
871+
field->static_var->value.char_value = (u2) pop_int(op_stack);
872+
field->static_var->type = VAR_SHORT;
873+
break;
874+
case 'I':
875+
/* integer */
876+
field->static_var->value.int_value = (u4) pop_int(op_stack);
877+
field->static_var->type = VAR_INT;
878+
break;
879+
case 'J':
880+
/* long integer */
881+
field->static_var->value.long_value = (u8) pop_int(op_stack);
882+
field->static_var->type = VAR_LONG;
883+
break;
884+
case 'S':
885+
/* signed short */
886+
field->static_var->value.short_value = (u2) pop_int(op_stack);
887+
field->static_var->type = VAR_SHORT;
888+
break;
889+
case 'Z':
890+
/* true or false */
891+
field->static_var->value.char_value = (u1) pop_int(op_stack);
892+
field->static_var->type = VAR_BYTE;
893+
break;
894+
case 'L':
895+
/* an instance of class ClassName */
896+
field->static_var->value.ptr_value = pop_ref(op_stack);
897+
field->static_var->type = VAR_PTR;
898+
break;
899+
default:
900+
fprintf(stderr, "Unknown field descriptor %c\n",
901+
field_descriptor[0]);
902+
exit(1);
903+
}
904+
pc += 3;
905+
break;
906+
}
792907

793908
/* Invoke instance method; dispatch based on class */
794909
case i_invokevirtual:

‎tests/Static.java‎

Lines changed: 23 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,23 @@
1+
public class Static {
2+
static int x, y, z;
3+
public static void main(String[] args) {
4+
x = 3;
5+
y = 4;
6+
z = 5;
7+
StaticA.x = 1;
8+
StaticB.x = Static.x + StaticA.x;
9+
System.out.println(Static.x);
10+
System.out.println(Static.y);
11+
System.out.println(Static.z);
12+
System.out.println(StaticA.x);
13+
System.out.println(StaticB.x);
14+
}
15+
}
16+
17+
class StaticA {
18+
static int x;
19+
}
20+
21+
class StaticB {
22+
static int x;
23+
}

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