cx16: fix macptr() signature and use it in diskio.f_read() for big increase in load speed

compiler/res/prog8lib/cx16/syslib.p8

@@ -363,7 +363,7 @@ romsub $fed5 = console_set_paging_message(uword msgptr @R0)  clobbers(A,X,Y)
 romsub $fecf = entropy_get() -> ubyte @A, ubyte @X, ubyte @Y
 romsub $fecc = monitor()  clobbers(A,X,Y)
 
-romsub $ff44 = macptr()  clobbers(A,X,Y)
+romsub $ff44 = macptr(ubyte length @A, uword buffer @XY)  clobbers(A) -> ubyte @Pc, uword @XY
 romsub $ff47 = enter_basic(ubyte cold_or_warm @Pc)  clobbers(A,X,Y)
 romsub $ff4d = clock_set_date_time(uword yearmonth @R0, uword dayhours @R1, uword minsecs @R2, ubyte jiffies @R3)  clobbers(A, X, Y)
 romsub $ff50 = clock_get_date_time()  clobbers(A, X, Y)  -> uword @R0, uword @R1, uword @R2, ubyte @R3   ; result registers see clock_set_date_time()

compiler/res/prog8lib/diskio.p8

@@ -239,6 +239,29 @@ close_end:
         }
 
         void c64.CHKIN(11)        ; use #11 as input channel again
+
+        if sys.target==16 {
+            ; commander X16 supports fast block-read via macptr() kernal call
+            uword size
+            while num_bytes {
+                size = 255
+                if num_bytes<size
+                    size = num_bytes
+                size = cx16.macptr(lsb(size), bufferpointer)
+                if_cs
+                    goto byte_read_loop     ; macptr block read not supported, do fallback loop
+                list_blocks += size
+                bufferpointer += size
+                num_bytes -= size
+                if c64.READST() & $40 {
+                    f_close()       ; end of file, close it
+                    break
+                }
+            }
+            return list_blocks  ; number of bytes read
+        }
+
+byte_read_loop:
         %asm {{
             lda  bufferpointer
             sta  m_in_buffer+1

docs/source/libraries.rst

@@ -139,6 +139,8 @@ Provides several routines that deal with disk drive I/O, such as:
 - load and save data from and to the disk
 - delete and rename files on the disk
 
+On the Commander X16 it tries to use that machine's fast kernal loading routines if possible.
+
 
 string
 ------

docs/source/todo.rst

@@ -3,8 +3,19 @@ TODO
 
 For next release
 ^^^^^^^^^^^^^^^^
-- cx16 diskio: use cx16 MACPTR() in f_read() to load stuff faster? (see its use in X16edit to fast load blocks)
-  note that it might fail on non sdcard files so have to make graceful degradation
+- why is this code so much larger:
+                uword xx
+                for xx in 0 to size-1 {
+                    gfx2.next_pixel(bitmapbuf[xx])
+                }
+  than this loop:
+                uword srcptr = bitmapbuf
+                repeat size {
+                    gfx2.next_pixel(@(srcptr))
+                    srcptr++
+                }
+  any difference between 6502 codegen and vm codegen?
+
 - pipe operator: (targets other than 'Virtual'): allow non-unary function calls in the pipe that specify the other argument(s) in the calls.  Already working for VM target.
 - add McCarthy evaluation to shortcircuit and/or expressions. First do ifs by splitting them up? Then do expressions that compute a value?
 - Inliner: also inline function call expressions, and remove it from the StatementOptimizer