{-----------------------------------------------------------------------+
|                                                                       |
|       Loading of programs over the serial port (with Arduino)         |
|                                                                       |
+-----------------------------------------------------------------------}
gcl0x

{ Setup }

{ Print a 5x8 character on screen with the built-in font
  Char must be in the 32-127 range (this is not checked) }
[def {PrintChar}
  Char=
  {Map ASCII code to offset in font table}
  82- [if<0 50+ i= \font32up
            else     i= \font82up] fontData= {Select low or high page}
  i 2<< i+             {Multiply by 5}
  fontData+ fontData=  {Add to page address to reach bitmap data for Char}

  {Draw 5 vertical slices: 5 using font data}
  32      \sysArgs0. {Blue}
  15      \sysArgs1. {Yellow}
  Pos     \sysArgs4:
  6+      Pos=
  \SYS_VDrawBits_134 \sysFn:
  $fb i= [do
    fontData 0? fontData<++ \sysArgs2. 134!!
    \sysArgs4<++
    i<++ i if<>0loop]
  ret
] PrintChar=

{ Display ready to load text }
$500c Pos=
[def {Ready to load}
  $52# $65# $61# $64# $79# $20# $74# $6f#
  $20# $6c# $6f# $61# $64# 0# ] Text=
[do Text, if<>0 Text<++ PrintChar! loop]

{ Put these in variable to save some code space below }
\SYS_LoaderNextByteIn_32  NextByteIn_32=
\SYS_LoaderPayloadCopy_34 PayloadCopy_34=

0 \sysArgs4.            {Clears the copy counter}
$590c A=                {Activity indicator}
$5b0c B=                {Buffer}
103 {'g'} \sysArgs2.    {Reset checksum}

{-----------------------------------------------------------------------+
|}$5a0c \vLR: ret{      Inside screen area                              |
+-----------------------------------------------------------------------}
$5a0c:

{ Loop }

[do
  {Receive the next transmission frame}
  B   \sysArgs0:                                {Input buffer}
  207 \sysArgs3. NextByteIn_32 \sysFn: 32!!     {Protocol byte}
  219 \sysArgs3.                       32!!     {Length, 6 new bits}
  235 \sysArgs3.                       32!!     {Low address}
  251 \sysArgs3.                       32!!     {High address}
                PayloadCopy_34 \sysFn: 34!!     {Copy previous bytes}
  2   \sysArgs3. NextByteIn_32 \sysFn: 32!!     {Payload 0}
  6   \sysArgs3.
  [do           PayloadCopy_34 \sysFn: 34!!     {Copy previous bytes}
                 NextByteIn_32 \sysFn: 32!!     {Payload 1-59}
    \sysArgs3, 4+ \sysArgs3.
    242^ if<>0loop]
  185 \sysArgs3.                       32!!     {Checksum byte}

  {Plot green or red indicator}
  \sysArgs2, [if=0 12 else 3] A.

  {Advance indicator and wrap around}
  A<, 11- 127& 12+ A<.

  {White indicator}
  63 A.

  {Check checksum and command, and execute if OK. Also reset checksum.}
  \SYS_LoaderProcessInput_48 \sysFn: 48!!
loop]

{
vgaY nextVideo videoY vCPU Comment
---- --------- ------ ---- -------
   0  videoE      179  Yes First vBlank
   1  videoE      181  Yes
   2  videoE      183  Yes
   3  videoE      185  Yes Byte 65 Checksum
  ..  ...         ...  Yes
  14  videoE      207  Yes Byte 0 Protocol ('L')
  ..  ...         ...  Yes
  20  videoE      219  Yes Byte 1 Length (6 bits)
  ..  ...         ...  Yes
  28  videoE      235  Yes Byte 2 Address L
  ..  ...         ...  Yes
  36  videoE      251  Yes Byte 3 Address H
  37  videoE      253  Yes
  38  videoE      255  Yes
  39  videoE        1  Yes
  40  videoE        1  Yes Last vBlank
  41  videoA->B     0   No Pixel
  42  videoB->C     0   No Pixel
  43  videoC->F     0   No Pixel
  44  videoF->A     2  Yes Byte 4 Payload 0
  45  videoA->B     2   No Pixel
  46  videoB->C     2   No Pixel
  47  videoC->F     2   No Pixel
  48  vidoeF->A     4  Yes
  49  videoA->B     4   No Pixel
  50  videoB->C     4   No Pixel
  51  videoC->F     4   No Pixel
  52  videoF->A     6  Yes Byte 5 Payload 1
  ..  ...         ...  ...
 513  videoA->B   236   No Pixel
 514  videoB->C   236   No Pixel
 515  videoC->F   236   No Pixel
 516  videoF->A   238  Yes Byte 64 Payload 59
 517  videoA->B   238   No Pixel
 518  videoB->C   238   No Pixel
 519  videoC->F   238   No Pixel
 520  videoF->E   238  Yes
}

{-----------------------------------------------------------------------+
|                                                                       |
+-----------------------------------------------------------------------}