allocator switches to nonzero_fill_calloc when malloc(0) is known to return NULL

Author: ZERICO2005

src/libc/allocator.src

@@ -1,82 +1,15 @@
 	assume	adl=1
 
 	section	.text
-	public	_malloc, _free, _realloc
 
-	public	_calloc
-
-if defined __TICE__
-
-; uses the hardware specific $E40000 memory location
-
-; void *calloc(size_t nmemb, size_t size)
-_calloc:
-	pop	de
-	pop	bc
-	ex	(sp), hl
-	push	bc
-	push	de
-	call	__imulu
-	push	hl
-	push	hl
-	call	_malloc
-	pop	bc	; reset SP
-	; test for NULL
-	add	hl, bc
-	or	a, a
-	sbc	hl, bc
-	pop	bc	; BC = size
-	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
-.finish:
-	pop	hl	; return value
-	ret
-
-else
-
-; makes no hardware assumptions
-
-; void *calloc(size_t nmemb, size_t size)
-_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
-
-end if
+	public	_malloc, _free, _realloc, _calloc
 
 if defined ALLOCATOR_SIMPLE
 
 _malloc := __simple_malloc
 _free := __simple_free
 _realloc := __simple_realloc
+_calloc := __nonzero_fill_calloc
 	extern  __simple_free
 	extern  __simple_malloc
 	extern  __simple_realloc
@@ -86,6 +19,7 @@ else if defined ALLOCATOR_STANDARD
 _malloc := __standard_malloc
 _free := __standard_free
 _realloc := __standard_realloc
+_calloc := __nonzero_fill_calloc
 	extern  __standard_malloc
 	extern  __standard_free
 	extern  __standard_realloc
@@ -95,11 +29,12 @@ else ; custom functions provided by the program
 _malloc := __custom_malloc
 _free := __custom_free
 _realloc := __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/calloc.src

@@ -0,0 +1,127 @@
+	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	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
+
+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
+	; assumes that malloc(0) returns NULL, so we can skip the check for zero bytes
+	push	hl
+	ex	de, hl
+	; large region of all zeros on the Ti84CE
+	ld	hl, $E40000
+	ldir
+	pop	hl
+	ret
+
+else
+
+; makes no hardware assumptions
+
+_nonzero_fill_calloc := _generic_calloc
+
+end if
+
+;-------------------------------------------------------------------------------
+
+    extern  __imulu
+    extern  _malloc
+    extern  _memset