109.636MHz/1B00: Many minor improvements

* Initial UART settings can be set by a generic.
* UART RX now only starts when there is a transition from high to low,
there are still problems (a frame error does not propagate to the rest
of the system, or is not detected), but this means when the UART line is
driven low then we do not get a series of invalid characters.
* The simulator now simulates the scrolling behavior of the VT100, along
with some more of the SGR codes the hardware supports.
* Some warnings have been fixed.
* The 'turn of reverse video' SGR has been fixed, it was $27 when it
should have been decimal 27, or $1B.
* We now erase three rows of text ahead of moving the base pointer text,
this prevents errant text from previous lines being displayed.
* An aid for test vector generation for the VT100 has been added, which
is a small GForth program that can be used to generate text with lots of
ANSI escape sequences in it.

NOTES:

Many of the more serious bugs in the VT100 have been fixed, however
there are still differences in how the simulator behaves, and how the
terminal emulators on my computer behave, which will need to be fixed.

Some of the bugs include:

* The AT-XY command does not seem to work after issue an erase display
command to the VT100, this likely due to the VT100 being too busy to
respond. This only appears when the UART FIFO is enabled, or when UART
output is disable (output only going to the VT100). This means it is
giving commands to the VT100 much quicker.
* The UART FIFO RX seems to work fine, although there are the same
problems with RX as there are without the FIFO (that is, we receive
invalid characters with high data rates). For the TX however, a
character seems to get stuck in the FIFO, it comes out, but then the
next character gets stuck, and so on. No data seems to be lost, but it
is annoying.
* There are some other VT100 differences between the hardware and how it
should behave, the test suite should help categorize and find the
issues.
* Other worrying things include the fact that the board seems to need
reprogramming multiple times before the system gets into a stable state.
Once in that stable state is appears to be very steady and stable, but
it can require multiple times before it becomes stable. Symptoms include
not booting, '? -4 stack underflow' being printed, only 'eForth V' being
printed, or reading from flash failing. I am not sure if the problem is
with my design, however reprogramming seems to fix the issue when it
does occur, with no other design changes needed.

Author: howerj

h2.c

@@ -969,11 +969,15 @@ static void terminal_parse_attribute(vt100_attribute_t * const a, const unsigned
 		a->foreground_color = WHITE;
 		a->background_color = BLACK;
 		return;
-	case 1: a->bold          = true; return;
-	case 4: a->under_score   = true; return;
-	case 5: a->blink         = true; return;
-	case 7: a->reverse_video = true; return;
-	case 8: a->conceal       = true; return;
+	case  1: a->bold          = true;  return;
+	case 22: a->bold          = false; return;
+	case  4: a->under_score   = true;  return;
+	case  5: a->blink         = true;  return;
+	case 25: a->blink         = false; return;
+	case  7: a->reverse_video = true;  return;
+	case 39: a->reverse_video = false; return;
+	case  8: a->conceal       = true;  return;
+	case 28: a->conceal       = false; return;
 	default:
 		if (v >= 30 && v <= 37)
 			a->foreground_color = v - 30;
@@ -1185,8 +1189,14 @@ void vt100_update(vt100_t *t, const uint8_t c) {
 			t->cursor++;
 		}
 		if (t->cursor >= t->size) {
-			terminal_attribute_block_set(t, t->size, &vt100_default_attribute);
-			memset(t->m, ' ', t->size);
+			const vt100_attribute_t *a = &vt100_default_attribute;
+			t->cursor -= t->width;
+			memmove(t->m, t->m + t->width, t->size - t->width);
+			memset((t->m + t->size) - t->width, ' ', t->width);
+			for (size_t i = 0; i < (t->size - t->width); i++)
+				t->attributes[i] = t->attributes[i + t->width];
+			for (size_t i = t->size - t->width; i < t->size; i++)
+				memcpy(&t->attributes[i], a, sizeof(*a));
 		}
 		t->cursor %= t->size;
 	}

h2.fth

@@ -191,10 +191,12 @@ location failed           "failed"      ( used in start up routine )
 : rx?  iUart uart? ; hidden ( -- c -1 | 0 : read in a character of input from UART )
 : ps2? iVT100 uart? ; hidden ( -- c -1 | 0 : PS/2 version of rx? )
 
-\ : not-busy @ $0800 and ; hidden
+\ TODO: 'rx?' should be called here, and any results queued, otherwise without
+\ a hardware FIFO we will block for potentially quite a long time if we are
+\ sending a lot of characters, never having a chance to read.
 : uart! ( c uart-register -- )
-\	begin dup @ $1000 and 0= until swap $2000 or swap ! ; hidden  \ check full
-	begin dup @ $0800 and until swap $2000 or swap ! ; hidden     \ check empty
+	begin dup @ $1000 and 0= until swap $2000 or swap ! ; hidden  \ check full
+\	begin dup @ $0800 and until swap $2000 or swap ! ; hidden     \ check empty
 
 : tx!  iUart uart! ; hidden
 : vga! iVT100 uart! ; hidden ( n a -- : output character to VT100 display )
@@ -536,7 +538,7 @@ location search-previous 0
 : , here dup cell+ ?dictionary cp! ! ; ( u -- )
 : doLit 0x8000 or , ; hidden
 : ?compile state @ 0= if 14 -throw exit then ; hidden ( fail if not compiling )
-\ @todo vector literal, amongst other words
+\ TODO vector literal, amongst other words
 : literal ( n -- : write a literal into the dictionary )
 	?compile
 	dup 0x8000 and ( n > $7fff ? )
@@ -811,7 +813,7 @@ in which the problem could be solved. )
 ( ==================== Strings ======================================= )
 
 ( ==================== Block Word Set ================================ )
-\ @todo 'blk' being set to zero should indicate an invalid block number, not -1
+\ TODO 'blk' being set to zero should indicate an invalid block number, not -1
 \ The usage of 'blk' is incorrect, it should be set to the block number
 \ most recently LOAD'ed, not the one most recently BLOCK'ed
 \ 
@@ -906,7 +908,7 @@ location tbl-2 $4143
        [char] L = if $7fff and . exit then
    drop ; hidden
 
-\ @todo print out immediate status, prettify output, ...
+\ TODO print out immediate status, prettify output, ...
 : see
  	token find 0= if 13 -throw exit then
 	cr

nvram.txt

@@ -385,18 +385,18 @@ red green blue + + constant white
 \ ==== Screen Saver ============================================
 \ An incredibly simple screen saver using ANSI Escape codes
 \ for placement and coloring of random characters
-
+base @ decimal
 : screen-saver ( -- )
   page
   begin
-    random 80 mod
-    random 40 mod at-xy
+    random 79 mod
+    random 38 mod at-xy
     random >char emit
     random 8  mod
-    ( random 1 and if background then )
-    color
+    random 1 and if background then
+    random 256 and ms color
   again ;
-
+base !
 
 ; ==== Game: YOU ARE DEAD (HELP) ===============================
 This is a clone of the one dimensional rogue like game

ram.vhd

@@ -38,7 +38,7 @@ entity ram_interface is
 		clk:               in    std_ulogic;
 		rst:               in    std_ulogic;
 
-		mem_addr_16_1:     in    std_ulogic_vector(16 downto 1);
+		mem_addr_16_1:     in    std_ulogic_vector(16 downto 2);
 		mem_addr_16_1_we:  in    std_ulogic;
 		mem_addr_26_17:    in    std_ulogic_vector(26 downto 17);
 		mem_addr_26_17_we: in    std_ulogic;
@@ -70,7 +70,7 @@ architecture rtl of ram_interface is
 	signal mem_addr_low:    std_ulogic_vector(mem_addr_16_1'range)  := (others => '0');
 	signal mem_addr_high:   std_ulogic_vector(mem_addr_26_17'range) := (others => '0');
 begin
-	mem_addr <= '0' & mem_addr_high & mem_addr_low(mem_addr_low'high downto mem_addr_low'low + 1);
+	mem_addr <= '0' & mem_addr_high & mem_addr_low;
 
 	mem_addr_16_1_reg: entity work.reg
 		generic map(g => g, N => mem_addr_16_1'length)

t/.gitignore

@@ -0,0 +1 @@
+*.ansi

t/ansi.fth

@@ -0,0 +1,72 @@
+\ RJH - ANSI TERMINAL TESTS / 2019. TESTED IN GFORTH
+\ Based around the definition for 'F' found here:
+\ https://www.forth.com/starting-forth/1-forth-stacks-dictionary/
+\
+\ This file is used to prepare test vectors for the VT-100 terminal emulator,
+\ a mini-language is make for drawing text and displaying colors.
+\
+ONLY FORTH DEFINITIONS DECIMAL
+
+WORDLIST CONSTANT COOL-TEXT ( <_< - way cool )
+COOL-TEXT >ORDER DEFINITIONS
+VARIABLE COOL-CHARACTER CHAR * COOL-CHARACTER !
+: BYE BYE ;
+: CR CR ;
+: {{ CR COOL-TEXT >ORDER DUP ;
+: >_> CHAR COOL-CHARACTER ! ;
+: <_< [CHAR] * COOL-CHARACTER ! ;
+: \ POSTPONE \ ;
+: .( POSTPONE .( ;
+
+: CSI $1B EMIT [CHAR] [ EMIT ; 
+: 10U. BASE @ >R DECIMAL 0 <# #S #> TYPE R> BASE ! ;
+: ANSI SWAP CSI 10U. EMIT ; ( N C -- )
+: AT-XY CSI 10U. $3B EMIT 10U. [CHAR] H EMIT ;
+: PAGE 2 [CHAR] J ANSI 1 1 AT-XY ;
+: SGR [CHAR] m ANSI ;
+
+: UP    [CHAR] A ANSI ;
+: DOWN  [CHAR] B ANSI ;
+: RIGHT [CHAR] C ANSI ;
+: LEFT  [CHAR] D ANSI ;
+
+0 CONSTANT BLACK 1 CONSTANT RED 2 CONSTANT GREEN 4 CONSTANT BLUE
+RED GREEN        + CONSTANT YELLOW
+    GREEN BLUE   + CONSTANT CYAN
+RED       BLUE   + CONSTANT MAGENTA
+RED GREEN BLUE + + CONSTANT WHITE
+: BACKGROUND $A + ;
+: COLOR $1E + SGR ;
+
+: BLINKY $5 SGR ;
+: UNBLINK $19 SGR ;
+: BOLD   $1  SGR ;
+: NORMAL $16 SGR ;
+: REVERSE $7 SGR ;
+: ESREVER $1B SGR ;
+
+: DOT     COOL-CHARACTER @ EMIT ;
+: DOTS    0 DO  DOT   LOOP ;
+: BLIP    1 DOWN DUP RIGHT    DOT DUP 2 * LEFT ;
+: BAR     1 DOWN DUP RIGHT 5 DOTS DUP 2 * LEFT ;
+: F       BAR BLIP BAR BLIP BLIP DROP 5 UP ;
+: C       BAR BLIP BLIP BLIP BAR DROP 5 UP ;
+: E       DUP F C ;
+: I       BLIP BLIP BLIP BLIP BLIP DROP 5 UP ;
+: O       DUP C 4 + I ;
+: A       DUP F 4 + I ;
+: _       4 DOWN BAR DROP 5 UP ;
+: TOP     BAR DROP 1 UP ;
+: U       DUP I DUP _ 4 + I ;
+: J       DUP _ 4 + I ;
+: L       DUP I _ ;
+: W       DUP L DUP 2 + I 4 + I ;
+: M       DUP I DUP 2 + I DUP 4 + I TOP ;
+: -       2 DOWN BAR DROP 3 UP ;
+: H       DUP I DUP - 4 + I ;
+: T       DUP TOP 2 + I ;
+: D       DUP I DROP ;
+
+: |       7 + DUP ;
+: }} DROP 6 DOWN PREVIOUS ;
+SEAL

t/eforth.fth

@@ -0,0 +1,3 @@
+\ Test setup code for eForth interpreter on the target
+: echos begin key emit switches until ;
+echos

t/hello.tst

@@ -0,0 +1,21 @@
+PAGE
+CR
+CR
+
+RED COLOR
+>_> . 5 {{ H | E | L | L | O }}
+BLUE COLOR
+>_> | 5 {{ H | E | L | L | O }}
+\ >_> / 5 {{ H | E | L | L | O }}
+CR CR
+
+0 SGR
+
+BLINKY .(      BLINK  ) UNBLINK BOLD .( BOLD ) NORMAL REVERSE .( REVERSE ) ESREVER CR
+CR
+MAGENTA BACKGROUND COLOR .(  MAGENTA   ) 
+YELLOW  BACKGROUND COLOR .(  YELLOW    ) 
+BLUE    BACKGROUND COLOR .(  BLUE      ) 
+
+0 SGR
+CR BYE

t/makefile

@@ -0,0 +1,14 @@
+SOURCES:=$(wildcard *.tst)
+OBJFILES=$(SOURCES:%.tst=%.ansi)
+
+.PHONY: all clean
+
+all: ${OBJFILES}
+
+%.ansi: %.tst ansi.fth eforth.fth 
+	cat eforth.fth > $@
+	gforth ansi.fth $< >> $@
+
+clean:
+	rm -fv *.ansi
+

t/readme.md

@@ -0,0 +1,16 @@
+# t/
+
+This folder is for tests. At the moment the tests are for the ANSI terminal
+emulator, but code that exercises the eForth interpreter on the running system
+could be added.
+
+The file [ansi.fth][] contains a framework for generated text files that
+contain ANSI Escape Sequences, which can be used to test that the VT100 module
+is working correctly.
+
+[eforth.fth][] contains code that should run on the target.
+
+All of this should be transmitted to the target over a UART.
+
+[ansi.fth]: ansi.fth
+[eforth.fth]: eforth.fth

top.vhd

@@ -520,7 +520,7 @@ begin
 	port map (
 		clk               =>  clk,
 		rst               =>  rst,
-		mem_addr_16_1     =>  io_dout,
+		mem_addr_16_1     =>  io_dout(io_dout'high downto 1),
 		mem_addr_16_1_we  =>  mem_addr_16_1_we,
 		mem_addr_26_17    =>  io_dout(9 downto 0),
 		mem_addr_26_17_we =>  mem_addr_26_17_we,