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Merge pull request #401 from greg-king5/void-size

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Make C's sizeof operator work with cc65's void variables.
This commit is contained in:
Oliver Schmidt 2017-03-12 20:06:34 +01:00 committed by GitHub
commit 0bbe4f56a5
7 changed files with 147 additions and 62 deletions
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47
doc/cc65.sgml
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@ -4,7 +4,7 @@
<title>cc65 Users Guide
<author><url url="mailto:uz@cc65.org" name="Ullrich von Bassewitz">,<newline>
<url url="mailto:gregdk@users.sf.net" name="Greg King">
<date>2016-06-11
<date>2017-02-27
<abstract>
cc65 is a C compiler for 6502 targets. It supports several 6502 based home
@ -687,30 +687,37 @@ This cc65 version has some extensions to the ISO C standard.
string.
<p>
<item> cc65 allows the initialization of <tt/void/ variables. This may be
used to create variable structures that are more compatible with
interfaces written for assembler languages. Here is an example:
<item> cc65 allows the initialization of <tt/void/ variables. This may be
used to create arbitrary structures that are more compatible with
interfaces written for assembler languages. Here is an example:
<tscreen><verb>
void GCmd = { (char)3, (unsigned)0x2000, (unsigned)0x3000 };
</verb></tscreen>
<tscreen><verb>
void GCmd = { (char)3, (unsigned)0x2000, (unsigned)0x3000 };
</verb></tscreen>
This will be translated as follows:
That will be translated as follows:
<tscreen><verb>
_GCmd:
.byte 3
.word $2000
.word $3000
</verb></tscreen>
<tscreen><verb>
_GCmd:
.byte 3
.word $2000
.word $3000
</verb></tscreen>
Since the variable is of type <tt/void/ you may not use it as is.
However, taking the address of the variable results in a <tt/void*/
which may be passed to any function expecting a pointer.
Since the variable is of type <tt/void/, you may not use it as-is.
However, taking the address of the variable results in a <tt/void*/
which may be passed to any function expecting a pointer. Also, the
<tt/sizeof/ operator will give the length of the initializer:
See the <url url="geos.html" name="GEOS library document"> for examples
on how to use this feature.
<p>
<tscreen><verb>
GLen = sizeof GCmd;
</verb></tscreen>
will assign the value 5 to <tt/GLen/.
See the <url url="geos.html" name="GEOS library document"> for examples
on how to use that feature.
<p>
<item> cc65 implements flexible array struct members as defined in the C99 ISO
standard. As an extension, these fields may be initialized. There are

7
src/cc65/datatype.c
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@ -389,7 +389,10 @@ unsigned SizeOf (const Type* T)
switch (UnqualifiedType (T->C)) {
case T_VOID:
return 0; /* Assume voids have size zero */
/* A void variable is a cc65 extension.
** Get its size (in bytes).
*/
return T->A.U;
/* Beware: There's a chance that this triggers problems in other parts
of the compiler. The solution is to fix the callers, because calling
@ -438,7 +441,7 @@ unsigned SizeOf (const Type* T)
/* Array with unspecified size */
return 0;
} else {
return T->A.L * SizeOf (T + 1);
return T->A.U * SizeOf (T + 1);
}
default:

10
src/cc65/declare.c
View File

@ -891,6 +891,7 @@ static void ParseTypeSpec (DeclSpec* D, long Default, TypeCode Qualifiers)
case TOK_VOID:
NextToken ();
D->Type[0].C = T_VOID;
D->Type[0].A.U = 0;
D->Type[1].C = T_END;
break;
@ -2114,7 +2115,7 @@ NextMember:
static unsigned ParseVoidInit (void)
static unsigned ParseVoidInit (Type* T)
/* Parse an initialization of a void variable (special cc65 extension).
** Return the number of bytes initialized.
*/
@ -2181,6 +2182,9 @@ static unsigned ParseVoidInit (void)
/* Closing brace */
ConsumeRCurly ();
/* Number of bytes determined by initializer */
T->A.U = Size;
/* Return the number of bytes initialized */
return Size;
}
@ -2216,8 +2220,8 @@ static unsigned ParseInitInternal (Type* T, int AllowFlexibleMembers)
case T_VOID:
if (IS_Get (&Standard) == STD_CC65) {
/* Special cc65 extension in non ANSI mode */
return ParseVoidInit ();
/* Special cc65 extension in non-ANSI mode */
return ParseVoidInit (T);
}
/* FALLTHROUGH */

9
test/err/void-empty.c Normal file
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@ -0,0 +1,9 @@
/*
!!DESCRIPTION!! Uninitialized void variables
!!ORIGIN!! cc65 regression tests
!!LICENCE!! Public Domain
!!AUTHOR!! Greg King
*/
void test;
const void list;

11
test/err/void-size2.c Normal file
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@ -0,0 +1,11 @@
/*
!!DESCRIPTION!! Size of void cast
!!ORIGIN!! cc65 regression tests
!!LICENCE!! Public Domain
!!AUTHOR!! Greg King
*/
unsigned test (void)
{
return sizeof ((void)12345);
}

56
test/val/void-size1.c Normal file
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@ -0,0 +1,56 @@
/*
!!DESCRIPTION!! Getting the size of a void-type variable (cc65 extension)
!!ORIGIN!! cc65 regression tests
!!LICENCE!! Public Domain
!!AUTHOR!! Greg King
*/
static const void list1 = {
(char)1,
(char)2,
(char)3,
(char)4,
(char)5,
(char)6,
(char)7,
(char)8,
(char)9,
(char)0
};
static void list2 = {
1,
2,
3,
4,
5,
6,
7,
8,
9,
0
};
void list3 = {
(char)1,
(char)2,
(char)3,
(char)4,
&list1,
(char)6,
(char)7,
(char)8,
(char)9,
&list2
};
/* We know that the expression is constant; don't tell us. */
#pragma warn (const-comparison, off)
int main (void)
{
return sizeof list1 != 10
|| sizeof list2 != 20
|| sizeof list3 != 12;
}

69
testcode/lib/atari/displaylist.c
View File

@ -1,59 +1,55 @@
/*
** testprogram for ANTIC instructions as defined in "_antic.h"
** test program for ANTIC instructions as defined in "_antic.h"
**
** 23-Feb-2017, Christian Krueger
*/
#include <conio.h>
#include <atari.h>
#include <peekpoke.h>
#include <string.h>
// code is only for testing purposes, as screen and display list are not aligned
// code is only for testing purposes, as screen and display list are not aligned,
// and jumps not set!
unsigned char DummyScreen[400];
void DisplayList = {
DL_BLK1,
DL_BLK2,
DL_BLK3,
DL_BLK4,
DL_BLK5,
DL_BLK6,
DL_BLK7,
DL_DLI(DL_BLK8),
DL_LMS(DL_CHR40x8x1),
DummyScreen,
DL_HSCROL(DL_CHR40x10x1),
DL_VSCROL(DL_CHR40x8x4),
DL_CHR40x16x4,
DL_LMS(DL_HSCROL(DL_VSCROL(DL_DLI(DL_CHR20x8x2)))),
DummyScreen+120,
DL_CHR20x16x2,
DL_MAP40x8x4,
DL_MAP80x4x2,
DL_MAP80x4x4,
DL_MAP160x2x2,
DL_MAP160x1x2,
DL_MAP160x2x4,
DL_MAP160x1x4,
DL_MAP320x1x1,
DL_JVB,
DL_JMP
DL_BLK1,
DL_BLK2,
DL_BLK3,
DL_BLK4,
DL_BLK5,
DL_BLK6,
DL_BLK7,
DL_DLI(DL_BLK8),
DL_LMS(DL_CHR40x8x1),
DummyScreen,
DL_HSCROL(DL_CHR40x10x1),
DL_VSCROL(DL_CHR40x8x4),
DL_CHR40x16x4,
DL_LMS(DL_HSCROL(DL_VSCROL(DL_DLI(DL_CHR20x8x2)))),
DummyScreen+120,
DL_CHR20x16x2,
DL_MAP40x8x4,
DL_MAP80x4x2,
DL_MAP80x4x4,
DL_MAP160x2x2,
DL_MAP160x1x2,
DL_MAP160x2x4,
DL_MAP160x1x4,
DL_MAP320x1x1,
DL_JVB,
DL_JMP
};
unsigned char dlend = 0;
/* We know that the sizeof expression is constant; don't tell us. */
#pragma warn (const-comparison, off)
int
main(void)
{
// unfortunately "sizeof()" doesn't work with void data
// (Error: Size of data type is unknown)
// so we trick with the addresses at front and end...
int returnValue = (((unsigned int)&dlend-(unsigned int)&DisplayList) != 28); // assure only one byte per instruction!
int returnValue = (sizeof DisplayList != 28); // assure only one byte per instruction!
clrscr();
if (returnValue)
@ -66,4 +62,3 @@ main(void)
return returnValue;
}