Add keyboard module.

.gitignore

@@ -0,0 +1 @@
+apple2e

Makefile

@@ -1,3 +1,6 @@
 CXXFLAGS=-Wall --std=c++11
 
 all: apple2e
+
+apple2e: apple2e.o keyboard.o
+	$(CXX) $(LDFLAGS) $^ -o $@ $(LDLIBS)

keyboard.cpp

@@ -0,0 +1,148 @@
+
+#include <stdio.h>
+#include <signal.h>
+#include <termios.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+
+#include "keyboard.h"
+
+static unsigned char last_key = 0;
+static bool strobe = false;
+
+struct termios oldtermios;
+
+static int ttyraw(int fd)
+{
+    /* Set terminal mode as follows:
+       Noncanonical mode - turn off ICANON.
+       Turn off signal-generation (ISIG)
+       including BREAK character (BRKINT).
+       Turn off any possible preprocessing of input (IEXTEN).
+       Turn ECHO mode off.
+       Disable CR-to-NL mapping on input.
+       Disable input parity detection (INPCK).
+       Disable stripping of eighth bit on input (ISTRIP).
+       Disable flow control (IXON).
+       Use eight bit characters (CS8).
+       Disable parity checking (PARENB).
+       Disable any implementation-dependent output processing (OPOST).
+       One byte at a time input (MIN=1, TIME=0).
+       */
+
+    // Save old settings.
+    struct termios newtermios;
+    if (tcgetattr(fd, &oldtermios) < 0) {
+        return -1;
+    }
+    newtermios = oldtermios;
+
+    newtermios.c_lflag &= ~(ECHO | ICANON | IEXTEN | ISIG);
+    /* OK, why IEXTEN? If IEXTEN is on, the DISCARD character
+       is recognized and is not passed to the process. This 
+       character causes output to be suspended until another
+       DISCARD is received. The DSUSP character for job control,
+       the LNEXT character that removes any special meaning of
+       the following character, the REPRINT character, and some
+       others are also in this category.
+       */
+
+    newtermios.c_iflag &= ~(BRKINT | ICRNL | INPCK | ISTRIP | IXON);
+    /* If an input character arrives with the wrong parity, then INPCK
+       is checked. If this flag is set, then IGNPAR is checked
+       to see if input bytes with parity errors should be ignored.
+       If it shouldn't be ignored, then PARMRK determines what
+       character sequence the process will actually see.
+
+       When we turn off IXON, the start and stop characters can be read.
+       */
+
+    newtermios.c_cflag &= ~(CSIZE | PARENB);
+    /* CSIZE is a mask that determines the number of bits per byte.
+       PARENB enables parity checking on input and parity generation
+       on output.
+       */
+
+    newtermios.c_cflag |= CS8;
+    /* Set 8 bits per character. */
+
+    newtermios.c_oflag &= ~(OPOST);
+    /* This includes things like expanding tabs to spaces. */
+
+    newtermios.c_cc[VMIN] = 1;
+    newtermios.c_cc[VTIME] = 0;
+
+    /* You tell me why TCSAFLUSH. */
+    if (tcsetattr(fd, TCSAFLUSH, &newtermios) < 0) {
+        return -1;
+    }
+
+    // Make the input non-blocking.
+    fcntl(fd, F_SETFL, O_NONBLOCK);
+
+    return 0;
+}
+
+
+int ttyreset(int fd)
+{
+    if (tcsetattr(fd, TCSAFLUSH, &oldtermios) < 0) {
+        return -1;
+    }
+
+    // Make blocking.
+    fcntl(fd, F_SETFL, 0);
+
+    return 0;
+}
+
+unsigned char get_keyboard_data_and_strobe()
+{
+    return last_key | (strobe ? 0x80 : 0x00);
+}
+
+unsigned char get_any_key_down_and_clear_strobe()
+{
+    strobe = false;
+
+    // Pretend that no keys are ever down right now.
+    return 0x00;
+}
+
+void start_keyboard()
+{
+    // Set raw mode on stdin.
+    if (ttyraw(0) < 0) {
+        fprintf(stderr,"Can't go to raw mode.\n");
+        exit(1);
+    }
+}
+
+void stop_keyboard()
+{
+    if (ttyreset(0) < 0) {
+        fprintf(stderr, "Cannot reset terminal!\n");
+        exit(-1);
+    }
+}
+
+void poll_keyboard()
+{
+    int i;
+    char c;
+
+    i = read(0, &c, 1);
+    if (i == -1) {
+        if (errno == EAGAIN) {
+            // Nothing to read.
+        } else {
+            printf("Got error reading from keyboard: %d\n\r", errno);
+            exit(1);
+        }
+    } else {
+        last_key = c;
+        strobe = true;
+    }
+}

keyboard.h

@@ -0,0 +1,19 @@
+#ifndef _KEYBOARD_H_
+#define _KEYBOARD_H_
+
+// Call this to go into raw mode.
+void start_keyboard();
+
+// Call this to get our of raw mode. Must be paired with start_keyboard().
+void stop_keyboard();
+
+// Call this regularly.
+void poll_keyboard();
+
+// Returns the ASCII value in the lower 7 bits and the strobe in the 8th bit.
+unsigned char get_keyboard_data_and_strobe();
+
+// Clears the strobe and pretends that no keys are down.
+unsigned char get_any_key_down_and_clear_strobe();
+
+#endif /* _KEYBOARD_H_ */