changed behaviour of malloc(0) and optimized calloc

src/libc/allocator.src

@@ -1,60 +1,40 @@
 	assume	adl=1
 
 	section	.text
-	public	_malloc, _free, _realloc
-
-	public	_calloc
-_calloc:
-	pop	de
-	pop	bc
-	ex	(sp),hl
-	push	bc
-	push	de
-	call	__imulu
-	push	hl
-	push	hl
-	call	_malloc
-	pop	de
-	add	hl,de
-	xor	a,a
-	sbc	hl,de
-	ld	e,a
-	push	de
-	push	hl
-	call	nz,_memset
-	pop	de
-	pop	de
-	pop	de
-	ret
+
+	public	_malloc, _free, _realloc, _calloc
 
 if defined ALLOCATOR_SIMPLE
 
 _malloc := __simple_malloc
 _free := __simple_free
 _realloc := __simple_realloc
-	extern  __simple_free
-	extern  __simple_malloc
-	extern  __simple_realloc
+_calloc := __nonzero_fill_calloc
+	extern	__simple_free
+	extern	__simple_malloc
+	extern	__simple_realloc
 
 else if defined ALLOCATOR_STANDARD
 
 _malloc := __standard_malloc
 _free := __standard_free
 _realloc := __standard_realloc
-	extern  __standard_malloc
-	extern  __standard_free
-	extern  __standard_realloc
+_calloc := __nonzero_fill_calloc
+	extern	__standard_malloc
+	extern	__standard_free
+	extern	__standard_realloc
 
 else ; custom functions provided by the program
 
 _malloc := __custom_malloc
 _free := __custom_free
 _realloc := __custom_realloc
-	extern  __custom_malloc
-	extern  __custom_free
-	extern  __custom_realloc
+_calloc := __generic_calloc
+	extern	__custom_malloc
+	extern	__custom_free
+	extern	__custom_realloc
 
 end if
 
-	extern	__imulu
-	extern	_memset
+	extern	__nonzero_fill_calloc
+	extern	__generic_calloc

src/libc/allocator_simple.src

@@ -4,13 +4,15 @@
 
 	public	__simple_malloc
 __simple_malloc:
+	; returns NULL when size is zero
 	pop	bc
 	ex	(sp),hl
 	push	bc
 	ld	de,(_heap_ptr)
+	dec	hl
 	add	hl,de
 	jr	c,.null
-	ld	bc,___heaptop
+	ld	bc,___heaptop-1
 	sbc	hl,bc
 	jr	nc,.null
 	add	hl,bc

src/libc/allocator_standard.c

@@ -21,7 +21,8 @@ void *_standard_malloc(size_t alloc_size)
 
     /* add size of block header to real size */
     const size_t size = alloc_size + sizeof(block_t);
-    if (size < alloc_size)
+    /* abort if alloc_size is 0 or size overflowed */
+    if (size <= alloc_size)
     {
         return NULL;
     }

src/libc/calloc.src

@@ -0,0 +1,163 @@
+	assume	adl=1
+
+; __nonzero_fill_calloc assumes that malloc(0) returns NULL
+; __generic_calloc makes no assumptions
+
+;-------------------------------------------------------------------------------
+
+	section	.text
+
+	public	__generic_calloc
+
+if defined __TICE__
+
+; uses TICE specific hardware/platform optimizations
+
+; void *calloc(size_t nmemb, size_t size)
+__generic_calloc:
+	pop	de
+	pop	bc
+	ex	(sp), hl
+	push	bc
+	push	de
+	call	__imulu
+	push	hl
+	push	hl
+	call	_malloc
+	pop	bc	; reset SP
+	pop	bc	; BC = size
+	; test for NULL
+	add	hl, bc
+	; or	a, a	; assumes that ptr + size does not overflow on TICE
+	sbc	hl, bc
+	ret	z	; return NULL
+	; inlined bzero
+	push	hl
+	ex	de, hl	; DE = dest
+	; test if the size is zero
+	scf
+	sbc	hl, hl
+	add	hl, bc
+	jr	nc, .finish
+	; large region of all zeros on the Ti84CE
+	ld	hl, $E40000	; HL = src
+	ldir
+	pop	hl	; return value
+	ret
+
+else
+
+; makes no hardware assumptions
+
+; void *calloc(size_t nmemb, size_t size)
+__generic_calloc:
+	pop	de
+	pop	bc
+	ex	(sp), hl
+	push	bc
+	push	de
+	call	__imulu
+	push	hl
+	push	hl
+	call	_malloc
+	pop	bc	; reset SP
+	pop	bc	; BC = size
+	; test for NULL
+	add	hl, bc
+	xor	a, a
+	sbc	hl, bc
+	ret	z	; return NULL
+	; inlined memset/bzero
+	cpi
+	add	hl, bc
+	ret	c	; size is zero
+	dec	hl
+	ld	(hl), a
+	ret	po	; size is one
+	push	hl
+	pop	de
+	dec	de
+	lddr
+	ret
+
+end if
+
+;-------------------------------------------------------------------------------
+
+	section	.text
+
+	public	__nonzero_fill_calloc
+
+if defined __TICE__
+
+; uses TICE specific hardware/platform optimizations
+
+; void *calloc(size_t nmemb, size_t size)
+__nonzero_fill_calloc:
+	pop	de
+	pop	bc
+	ex	(sp), hl
+	push	bc
+	push	de
+	call	__imulu
+	push	hl
+	push	hl
+	call	_malloc
+	pop	bc	; reset SP
+	pop	bc	; BC = size
+	; test for NULL
+	add	hl, bc
+	; or	a, a	; assumes that ptr + size does not overflow on TICE
+	sbc	hl, bc
+	ret	z	; return NULL
+	; inlined bzero
+	; assumes that malloc(0) returns NULL, so we can skip the check for zero size
+	push	hl
+	ex	de, hl	; DE = dest
+	; large region of all zeros on the Ti84CE
+	ld	hl, $E40000	; HL = src
+	ldir
+	pop	hl	; return value
+	ret
+
+else
+
+; makes no hardware assumptions
+
+; void *calloc(size_t nmemb, size_t size)
+__nonzero_fill_calloc:
+	pop	de
+	pop	bc
+	ex	(sp), hl
+	push	bc
+	push	de
+	call	__imulu
+	push	hl
+	push	hl
+	call	_malloc
+	pop	bc	; reset SP
+	pop	bc	; BC = size
+	; test for NULL
+	add	hl, bc
+	xor	a, a
+	sbc	hl, bc
+	ret	z	; return NULL
+	; inlined memset/bzero
+	; assumes that malloc(0) returns NULL, so we can skip the check for zero size
+	add	hl, bc
+	cpd
+	ld	(hl), a
+	ret	po	; size is one
+	push	hl
+	pop	de
+	dec	de
+	lddr
+	ret
+
+end if
+
+;-------------------------------------------------------------------------------
+
+	extern	__imulu
+	extern	_malloc
+	extern	_memset

test/standalone/asprintf_fprintf/src/main.c

@@ -418,6 +418,12 @@ int memccpy_tests(void) {
         return __LINE__;
     }
 
+    /* check that no crashes occur with small calloc sizes */
+    buf = (char*)calloc(1, sizeof(char));
+    free(buf);
+    buf = (char*)calloc(0, sizeof(char));
+    free(buf);
+
     buf = (char*)calloc(file_size + 1, sizeof(char));
     if (buf == NULL) {
         perror("calloc failure");