Adds the InputConsole and a test program for it - echo.asm

.vscode/launch.json

@@ -60,7 +60,7 @@
                     "kind": "bin"
                 }
             },
-            "args": ["simple_test_machine\\programs\\hello.rw"],
+            "args": ["simple_test_machine\\programs\\echo.rw"],
             "cwd": "${workspaceFolder}"
         },
     ]

simple_test_machine/programs/echo.asm

@@ -0,0 +1,57 @@
+
+; echo example - takes input and then prints it back out
+; This is for testing the InputConsole of the Simple Test Machine
+; by Joey Pollack
+
+; assemble with win2c64 (or lin2c64, or mac2c64) using the -R option
+; win2c64 found here:
+; https://www.aartbik.com/retro.php
+
+; CONSTANTS
+con_out         .equ    $1100   ; console output buffer address
+con_in          .equ    $1200   ; console input buffer address
+con_flags       .equ    $009A   ; console flags address
+prt_str_flag    .equ    $0002   ; print string flag
+prmp_input_flag .equ 	$0004   ; prompt for input flag
+
+; MAIN
+main    .org   $0200   ; program load address for the Simple Test Machine
+        ldx    #0
+loop    lda    text,x
+        sta    con_out,x    
+        inx
+        cpx    #12		; length of text
+        bne    loop 
+
+        ; null terminate the string
+        lda #0           
+        sta con_out,x          
+
+        ; Print the prompt message
+        lda con_flags           ; load the console flags
+        ora #prt_str_flag       ; set the print string flag
+        sta con_flags           ; store the modified flags
+
+        ; Prompt the user for input
+        lda con_flags 		; load the console flags
+        ora #prmp_input_flag	; set the prompt for input flag
+        sta con_flags		; store the flags back to memory - this should trigger reading input
+
+        ; Echo the input back to the console
+        ; iterate the input buffer and move each byte to the output buffer
+        ldx     #0              ; initialize the offset counter
+loop2   lda     con_in,x        ; load byte from the input buffer, offset by x register
+        sta     con_out,x       ; store byte into output buffer, offset by x register
+        inx                     ; increment the offset
+        cmp     #0              ; check for the null byte
+        bne     loop2           ; branch back to loop2 if we are not at the null byte yet        
+
+        lda con_flags           ; load the console flags
+        ora #prt_str_flag       ; set the print string flag
+        sta con_flags           ; store the modified flags
+
+        ; End the program
+        rts            ; 0x60 
+
+; MEMORY
+text            .byte  "Enter Text: "

simple_test_machine/src/machine.rs

@@ -1,21 +1,22 @@
 
 
-use std::str;
+use std::{io, str};
 
 //|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
-//				USED MEMORY ADDRESSES
+//				MEMORY ADDRESSES AND FLAGS
 //|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 const PROGRAM_START_ADDR: u16 = 0x0200;     // Program code starts on page 2
 const CPU_RESET_START_ADDR: u16 = 0xFFFC;   // This is where the cpu looks for the address to start executing code at
 
 pub const OUTPUT_BUF_ADDR: u16 = 0x1100;    // Output buffer -- Put values to be printed at this location!
 pub const INPUT_BUF_ADDR: u16 = 0x1200;     // Input buffer
+pub const INPUT_BUF_SIZE: u16 = 0x00FF;     // Input buffer is 255 bytes
 
 pub const CONSOLE_FLAGS_ADDR: u16 = 0x009A; // Grouping all of the console flags into a single byte
 
 pub const PRINT_BYTE_FLAG: u8 = 0x01;    // Then set one of these flags to trigger the print
 pub const PRINT_STR_FLAG:  u8 = 0x02;    //      and indicate what type is being printed.
-pub const READ_KB_FLAG:    u8 = 0x04;    // Set this address to 1 to request user input from the keyboard
+pub const READ_LINE_FLAG:    u8 = 0x04;    // Set this flag to request user input from the keyboard
 
 /////////////////////////////////////////////////////////////////////
 //				BUS
@@ -104,15 +105,14 @@ impl OutputConsole
         }
 
         // Check for byte to print
-        let mut flag = bus.read(CONSOLE_FLAGS_ADDR);
-        if (flag & PRINT_BYTE_FLAG)!= 0
+        else if (value & PRINT_BYTE_FLAG)!= 0
         {
             // read the byte
             let byte = bus.read(OUTPUT_BUF_ADDR);
 
             // reset the flag
-            flag &= !(PRINT_BYTE_FLAG);
-            bus.write(CONSOLE_FLAGS_ADDR, flag);
+            value &= !(PRINT_BYTE_FLAG);
+            bus.write(CONSOLE_FLAGS_ADDR, value);
 
             // print the byte
             println!("{}", byte as u8);
@@ -132,7 +132,37 @@ impl InputConsole
 {
     fn clock(_cpu: &mut R6502, bus: &mut TBus)
     {
+        // Check input request flag
+        let mut value = bus.read(CONSOLE_FLAGS_ADDR);
+        if (value & READ_LINE_FLAG) != 0
+        {
+            let mut buffer = String::new();
+            let stdin = io::stdin();
+            stdin.read_line(&mut buffer).expect("Failed to read input from the console");
 
+            // Make sure the string will fit in the input buffer
+            if (buffer.len() + 1) as u16 >= INPUT_BUF_SIZE
+            {
+                // TODO: Change this to set an error flag instead of printing. This way
+                //          the program can detect and handle these errors.
+                println!("ERROR: InputConsole cannot store input string into memory, string is too large");
+                return;
+            }
+
+            // Store input in the input buffer
+            for (i, byte) in buffer.chars().enumerate()
+            {
+                bus.write(INPUT_BUF_ADDR + (i as u16), byte as u8);
+            }
+
+            // Add the null byte to the end
+            bus.write(INPUT_BUF_ADDR + buffer.len() as u16, 0);
+
+            // reset the flag
+            value &= !(READ_LINE_FLAG);
+            bus.write(CONSOLE_FLAGS_ADDR, value);
+
+        }
     }
 }
 
@@ -185,10 +215,7 @@ impl TestMachine
         {
             self.cpu.clock(&mut self.bus);
             OutputConsole::clock(&mut self.cpu, &mut self.bus);
-
-            // TODO: Check if the input flag is set (need to choose a memory location for it)
-            //          if it's set, prompt for input and copy the input into memory (need an address for that too)
-            //  ACTUALLY: Move that logic into a new module (InputConsole) and just call clock() (like OutputConsole)
+            InputConsole::clock(&mut self.cpu, &mut self.bus);
         }
     }
 }