Add callocate routine

This implements the equivalent for C calloc() function.
Changes alloc.asm and related licenses from BSD to MIT.
Also fixes some typos in alloc.bas comments.

Author: boriel

library-asm/alloc.asm

@@ -3,11 +3,11 @@
 ;  (a.k.a. Boriel) 
 ;  http://www.boriel.com
 ;
-; This ASM library is licensed under the BSD license
+; This ASM library is licensed under the MIT license
 ; you can use it for any purpose (even for commercial
 ; closed source programs).
 ;
-; Please read the BSD license on the internet
+; Please read the MIT license on the internet
 
 ; ----- IMPLEMENTATION NOTES ------
 ; The heap is implemented as a linked list of free blocks.
@@ -183,4 +183,3 @@ __MEM_SUBTRACT:
             
         ENDP
 
-

library-asm/calloc.asm

@@ -0,0 +1,45 @@
+; vim: ts=4:et:sw=4:
+; Copyleft (K) by Jose M. Rodriguez de la Rosa
+;  (a.k.a. Boriel)
+;  http://www.boriel.com
+;
+; This ASM library is licensed under the MIT license
+; you can use it for any purpose (even for commercial
+; closed source programs).
+;
+; Please read the MIT license on the internet
+
+#include once <alloc.asm>
+
+
+; ---------------------------------------------------------------------
+; MEM_CALLOC
+;  Allocates a block of memory in the heap, and clears it filling it
+;  with 0 bytes
+;
+; Parameters
+;  BC = Length of requested memory block
+;
+; Returns:
+;  HL = Pointer to the allocated block in memory. Returns 0 (NULL)
+;       if the block could not be allocated (out of memory)
+; ---------------------------------------------------------------------
+__MEM_CALLOC:
+        push bc
+        call __MEM_ALLOC
+        pop bc
+        ld a, h
+        or l
+        ret z  ; No memory
+        ld (hl), 0
+        dec bc
+        ld a, b
+        or c
+        ret z  ; Already filled (1 byte-length block)
+        ld d, h
+        ld e, l
+        inc de
+        push hl
+        ldir
+        pop hl
+        ret

library/alloc.bas

@@ -26,7 +26,7 @@ REM Avoid recursive / multiple inclusion
 '
 ' Returns:
 '	16 bits (pointer) unsigned integer. NULL is returned if not
-'	enough memory to alloc the block
+'	enough memory to allocate the block
 ' ----------------------------------------------------------------
 function FASTCALL allocate(byval n as uinteger) as uinteger
 	' This is a FastCall function. This means:
@@ -41,6 +41,34 @@ function FASTCALL allocate(byval n as uinteger) as uinteger
 end function
 
 
+' ----------------------------------------------------------------
+' function calloc
+'
+' Allocates the requested bytes in the heap (dynamic memory) and
+' returns the address (16 bit, unsigned) of the new bloc. If
+' no memory, NULL (0) is returned.
+' The allocated block is cleared (filled with 0's) upon return.
+'
+' Parameters:
+'     n: number of bytes
+'
+' Returns:
+'	16 bits (pointer) unsigned integer. NULL is returned if not
+'	enough memory to allocate the block
+' ----------------------------------------------------------------
+function FASTCALL callocate(byval n as uinteger) as uinteger
+	' This is a FastCall function. This means:
+	'     1.- The 16 bit 'n' parameter is received in hl
+	'     2.- Can return at any point with "ret"
+	'     3.- The result (16bit) must be returned in HL
+	asm
+	ld b, h
+	ld c, l
+	jp __MEM_CALLOC ; Since calloc is FASTCALL, we can return from there
+	end asm
+end function
+
+
 ' ----------------------------------------------------------------
 ' sub free
 '
@@ -146,7 +174,7 @@ function FASTCALL maxavail as uInteger
     LOCAL LOOP, CONT
 
     ld hl, ZXBASIC_MEM_HEAP
-    ld de, 0 ; Size acumulator
+    ld de, 0 ; Size accumulator
 
 LOOP:
     ; BC = (HL) = Block size
@@ -193,6 +221,7 @@ end function
 #require "alloc.asm"
 #require "free.asm"
 #require "realloc.asm"
+#require "calloc.asm"
 
 #endif