commit de2dc16c6af24e03ed1b03768c80c47bef532e21
Author: Jeremy Rand <jeremy@halcyontouch.com>
Date:   Fri Jul 20 09:30:41 2012 -0500

    Initial commit

diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..adb74e8
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,37 @@
+BIN=curta.bin
+
+GEN_ASM=a2e.stdjoy.s a2e.hi.s
+SRCS=$(wildcard *.c)
+ASM=$(filter-out $(GEN_ASM),$(wildcard *.s)) $(GEN_ASM)
+
+C_OBJS=$(SRCS:.c=.o)
+ASM_OBJS=$(ASM:.s=.o)
+OBJS=$(C_OBJS) $(ASM_OBJS)
+
+PLATFORM=apple2enh
+#PLATFORM_CFG=-C $(PLATFORM)-loader.cfg
+PLATFORM_CFG=--start-addr '$$4000'
+
+MAPFILE=curta.map
+
+all:    $(BIN)
+
+a2e.stdjoy.s:
+	co65 --code-label _a2e_stdjoy -o $@ $(CC65_HOME)/joy/a2e.stdjoy.joy
+
+a2e.hi.s:
+	co65 --code-label _a2e_hi -o $@ $(CC65_HOME)/tgi/a2e.hi.tgi
+
+%.o:	%.s
+	ca65 -t $(PLATFORM) -o $@ $<
+
+$(BIN): $(ASM_OBJS) $(SRCS)
+	cl65 -t $(PLATFORM) $(PLATFORM_CFG) --mapfile $(MAPFILE) -o $(BIN).tmp $(SRCS) $(addprefix --obj ,$(ASM_OBJS)) 
+	dd if=$(BIN).tmp of=$(BIN) bs=4 skip=1
+	rm -f $(BIN).tmp
+
+clean:
+	rm -f $(BIN) $(OBJS) $(GEN_ASM) $(MAPFILE)
+
+install: $(BIN)
+	cp $(BIN) ~/Documents/"Apple ]["/Transfer
diff --git a/curtaEm.c b/curtaEm.c
new file mode 100644
index 0000000..b1721a3
--- /dev/null
+++ b/curtaEm.c
@@ -0,0 +1,531 @@
+#include <stdint.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <ctype.h>
+#include <apple2.h>
+#include <apple2enh.h>
+#include <conio.h>
+#include <joystick.h>
+#include <tgi.h>
+#include <tgi/tgi-mode.h>
+
+
+// Extern symbols for joystick and graphics drivers
+extern char a2e_stdjoy;
+extern char a2e_hi;
+
+#define NUM_OPERAND_DIGITS 11
+#define NUM_RESULT_DIGITS 15
+#define NUM_COUNTER_DIGITS 8
+
+typedef int8_t tDigit;
+typedef int8_t tDigitPos;
+typedef int8_t tAction;
+typedef int8_t tJoyPos;
+
+#define ACTION_OPERAND_SHIFT_LEFT 0
+#define ACTION_OPERAND_SHIFT_RIGHT 1
+#define ACTION_OPERAND_INC 2
+#define ACTION_OPERAND_DEC 3
+#define ACTION_RESULT_SHIFT_LEFT 4
+#define ACTION_RESULT_SHIFT_RIGHT 5
+#define ACTION_ADD 6
+#define ACTION_SUBTRACT 7
+#define ACTION_CLEAR 8
+#define ACTION_NULL 9
+
+#define JOY_POS_CENTER 0
+#define JOY_POS_DOWN 1
+#define JOY_POS_DOWN_LEFT 2
+#define JOY_POS_LEFT 3
+#define JOY_POS_UP_LEFT 4
+#define JOY_POS_UP 5
+#define JOY_POS_UP_RIGHT 6
+#define JOY_POS_RIGHT 7
+#define JOY_POS_DOWN_RIGHT 8
+
+tDigit operand[NUM_OPERAND_DIGITS];
+tDigit result[NUM_RESULT_DIGITS];
+tDigit counter[NUM_COUNTER_DIGITS];
+
+// Ranges from 0 to 8
+#define RESULT_POS_MIN 0
+#define RESULT_POS_MAX 8
+tDigitPos resultPos;
+tDigitPos selectedOperand;
+
+
+#define OPERAND_COLOR COLOR_WHITE
+#define OPERAND_OFFSET 4
+#define SLIDER_BAR_COLOR COLOR_BLUE
+#define SELECTED_SLIDER_BAR_COLOR COLOR_VIOLET
+#define SLIDER_COLOR COLOR_ORANGE
+#define SELECTED_SLIDER_COLOR COLOR_BLACK
+#define SLIDER_X_BORDER 8
+#define SLIDER_Y_BORDER 15
+#define SLIDER_BAR_WIDTH 12
+#define SLIDER_BAR_HEIGHT 130
+#define SLIDER_BAR_SPACING 20
+
+#define SLIDER_X_OFFSET 2
+#define SLIDER_Y_OFFSET 1
+#define SLIDER_WIDTH 8
+#define SLIDER_HEIGHT 11
+#define SLIDER_Y_SPACING (SLIDER_HEIGHT + (2 * SLIDER_Y_OFFSET))
+
+
+void drawOperand(tDigitPos pos);
+
+
+void clearDevice(void)
+{
+    tDigitPos pos;
+    
+    for (pos = 0; pos < NUM_RESULT_DIGITS; pos++) {
+        result[pos] = 0;
+    }
+    for (pos = 0; pos < NUM_COUNTER_DIGITS; pos++) {
+        counter[pos] = 0;
+    }
+}
+
+
+void resetDevice(void)
+{
+    tDigitPos pos;
+
+    clearDevice();
+    resultPos = 0;
+    selectedOperand = 0;
+
+    for (pos = 0; pos < NUM_OPERAND_DIGITS; pos++) {
+        result[pos] = 0;
+    }
+}
+    
+
+void incOperandPos(tDigitPos pos)
+{
+    if (pos >= NUM_OPERAND_DIGITS)
+        return;
+
+    if (operand[pos] == 9)
+        return;
+
+    operand[pos]++;
+    drawOperand(pos);
+}
+
+
+void decOperandPos(tDigitPos pos)
+{
+    if (pos >= NUM_OPERAND_DIGITS)
+        return;
+
+    if (operand[pos] == 0)
+        return;
+
+    operand[pos]--;
+    drawOperand(pos);
+}
+
+
+void shiftOperandPos(bool left)
+{
+    tDigitPos newPos = selectedOperand;
+    tDigitPos oldPos = selectedOperand;
+
+    if (left) {
+        newPos++;
+        if (newPos >= NUM_OPERAND_DIGITS) {
+            return;
+        }
+    } else {
+        newPos--;
+        if (newPos < 0) {
+            return;
+        }
+    }
+
+    selectedOperand = newPos;
+    drawOperand(oldPos);
+    drawOperand(newPos);
+}
+
+void shiftResultPos(bool left)
+{
+    if (left) {
+        if (resultPos + 1 >= RESULT_POS_MAX)
+            return;
+        resultPos++;
+    } else {
+        if (resultPos <= RESULT_POS_MIN)
+            return;
+        resultPos--;
+    }
+}
+
+
+void subOperation(tDigit *digits, tDigitPos pos, tDigitPos maxPos, tDigit toSub)
+{
+    if (toSub == 0)
+        return;
+
+    if (pos >= maxPos)
+        return;
+
+    digits[pos]-=toSub;
+    while (digits[pos] < 0) {
+        digits[pos]+=10;
+        subOperation(digits, pos+1, maxPos, 1);
+    }
+}
+
+
+void addOperation(tDigit *digits, tDigitPos pos, tDigitPos maxPos, tDigit toAdd)
+{
+    if (toAdd == 0)
+        return;
+
+    if (pos >= maxPos)
+        return;
+
+    digits[pos]+=toAdd;
+    while (digits[pos] > 9) {
+        digits[pos]-=10;
+        addOperation(digits, pos+1, maxPos, 1);
+    }
+}
+
+
+void crank(bool isSubtract)
+{
+    tDigitPos pos;
+    if (isSubtract) {
+        subOperation(counter, resultPos, NUM_COUNTER_DIGITS, 1);
+        for (pos = 0; pos < NUM_OPERAND_DIGITS; pos++) {
+            subOperation(result, resultPos+pos, NUM_RESULT_DIGITS, operand[pos]);
+        }
+    } else {
+        addOperation(counter, resultPos, NUM_COUNTER_DIGITS, 1);
+        for (pos = 0; pos < NUM_OPERAND_DIGITS; pos++) {
+            addOperation(result, resultPos+pos, NUM_RESULT_DIGITS, operand[pos]);
+        }
+    }
+}
+
+
+void printDigits(char *label, tDigit *digits, tDigitPos maxPos)
+{
+    tDigitPos pos;
+
+    printf("%7s:", label);
+    for(pos = maxPos - 1; pos >= 0; pos--) {
+        printf(" %d", digits[pos]);
+    }
+    printf("\n");
+}
+
+
+void printState(void)
+{
+    tDigitPos pos;
+    printDigits("Counter", counter, NUM_COUNTER_DIGITS);
+    printDigits("Result", result, NUM_RESULT_DIGITS);
+
+    printf("      ");
+    for(pos = 0; pos < NUM_RESULT_DIGITS - resultPos; pos++) {
+        printf("  ");
+    }
+    printf(" ^\n");
+}
+
+
+void drawOperand(tDigitPos pos)
+{
+    char xPos;
+    char buffer[2];
+    tDigit digit;
+
+    if (pos < 0)
+        return;
+    if (pos >= NUM_OPERAND_DIGITS)
+        return;
+
+    xPos = SLIDER_X_BORDER + (SLIDER_BAR_SPACING * (NUM_OPERAND_DIGITS - pos - 1));
+    digit = operand[pos];
+
+    // Clear old bar
+    tgi_setcolor(COLOR_BLACK);
+    tgi_bar(xPos, 0, xPos + SLIDER_BAR_WIDTH, SLIDER_Y_BORDER + SLIDER_BAR_HEIGHT);
+    
+    // Draw text label
+    buffer[0] = digit + '0';
+    buffer[1] = '\0';
+    tgi_setcolor(OPERAND_COLOR);
+    tgi_outtextxy(xPos + OPERAND_OFFSET, 0, buffer);
+
+    // Draw slider bar
+    if (selectedOperand == pos) {
+        tgi_setcolor(SELECTED_SLIDER_BAR_COLOR);
+    } else {
+        tgi_setcolor(SLIDER_BAR_COLOR);
+    }
+    tgi_bar(xPos, SLIDER_Y_BORDER, xPos + SLIDER_BAR_WIDTH, SLIDER_Y_BORDER + SLIDER_BAR_HEIGHT);
+
+    // Draw slider
+    if (selectedOperand == pos) {
+        tgi_setcolor(SELECTED_SLIDER_COLOR);
+    } else {
+        tgi_setcolor(SLIDER_COLOR);
+    }
+    tgi_bar(xPos + SLIDER_X_OFFSET,
+            SLIDER_Y_BORDER + SLIDER_Y_OFFSET + (SLIDER_Y_SPACING * digit),
+            xPos + SLIDER_X_OFFSET + SLIDER_WIDTH,
+            SLIDER_Y_BORDER + SLIDER_Y_OFFSET + (SLIDER_Y_SPACING * digit) + SLIDER_HEIGHT);
+}
+
+
+tJoyPos getJoyPos(char joyState)
+{
+    if (JOY_BTN_UP(joyState)) {
+        if (JOY_BTN_LEFT(joyState)) {
+            return JOY_POS_UP_LEFT;
+        } else if (JOY_BTN_RIGHT(joyState)) {
+            return JOY_POS_UP_RIGHT;
+        } else {
+            return JOY_POS_UP;
+        }
+    } else if (JOY_BTN_DOWN(joyState)) {
+        if (JOY_BTN_LEFT(joyState)) {
+            return JOY_POS_DOWN_LEFT;
+        } else if (JOY_BTN_RIGHT(joyState)) {
+            return JOY_POS_DOWN_RIGHT;
+        } else {
+            return JOY_POS_DOWN;
+        }
+    } else {
+        if (JOY_BTN_LEFT(joyState)) {
+            return JOY_POS_LEFT;
+        } else if (JOY_BTN_RIGHT(joyState)) {
+            return JOY_POS_RIGHT;
+        } else {
+            return JOY_POS_CENTER;
+        }
+    }
+}
+
+
+tAction getNextAction(void)
+{
+    static bool firstCall = true;
+    static char oldJoyState;
+    static tJoyPos oldJoyPos;
+    static unsigned int possibleActions = 0xffff;
+
+    char joyState;
+    tJoyPos joyPos;
+    tAction result = ACTION_NULL;
+
+    if (firstCall) {
+        oldJoyState = joy_read(JOY_1);
+        oldJoyPos = getJoyPos(oldJoyState);
+        firstCall = false;
+        return result;
+    }
+
+    joyState = joy_read(JOY_1);
+    joyPos = getJoyPos(joyState);
+
+    if ((JOY_BTN_FIRE2(oldJoyState) &&
+        (!JOY_BTN_FIRE2(joyState)))) {
+        oldJoyState = joyState;
+        result = ACTION_CLEAR;
+    } else if (joyPos == oldJoyPos) {
+        oldJoyState = joyState;
+        return result;
+    } else if (oldJoyPos == JOY_POS_CENTER) {
+        if (joyPos == JOY_POS_LEFT) {
+            if (JOY_BTN_FIRE(joyState)) {
+                possibleActions = (1 << ACTION_RESULT_SHIFT_LEFT);
+            } else {
+                possibleActions = (1 << ACTION_OPERAND_SHIFT_LEFT);
+            }
+        } else if (joyPos == JOY_POS_RIGHT) {
+            if (JOY_BTN_FIRE(joyState)) {
+                possibleActions = (1 << ACTION_RESULT_SHIFT_RIGHT);
+            } else {
+                possibleActions = (1 << ACTION_OPERAND_SHIFT_RIGHT);
+            }
+        } else if (joyPos == JOY_POS_UP) {
+            possibleActions = (1 << ACTION_OPERAND_DEC);
+        } else if (joyPos == JOY_POS_DOWN) {
+            possibleActions = (1 << ACTION_OPERAND_INC);
+            if (JOY_BTN_FIRE(joyState)) {
+                possibleActions |= (1 << ACTION_SUBTRACT);
+            } else {
+                possibleActions |= (1 << ACTION_ADD);
+            }
+        }
+    } else {
+        if (possibleActions & (1 << ACTION_OPERAND_SHIFT_LEFT)) {
+            if (joyPos == JOY_POS_CENTER) {
+                result = ACTION_OPERAND_SHIFT_LEFT;
+            } else {
+                possibleActions &= (~(1 << ACTION_OPERAND_SHIFT_LEFT));
+            }
+        }
+
+        if (possibleActions & (1 << ACTION_OPERAND_SHIFT_RIGHT)) {
+            if (joyPos == JOY_POS_CENTER) {
+                result = ACTION_OPERAND_SHIFT_RIGHT;
+            } else {
+                possibleActions &= (~(1 << ACTION_OPERAND_SHIFT_RIGHT));
+            }
+        }
+
+        if (possibleActions & (1 << ACTION_OPERAND_INC)) {
+            if (joyPos == JOY_POS_CENTER) {
+                result = ACTION_OPERAND_INC;
+            } else {
+                possibleActions &= (~(1 << ACTION_OPERAND_INC));
+            }
+        }
+
+        if (possibleActions & (1 << ACTION_OPERAND_DEC)) {
+            if (joyPos == JOY_POS_CENTER) {
+                result = ACTION_OPERAND_DEC;
+            } else {
+                possibleActions &= (~(1 << ACTION_OPERAND_DEC));
+            }
+        }
+
+        if (possibleActions & (1 << ACTION_RESULT_SHIFT_LEFT)) {
+            if (joyPos == JOY_POS_CENTER) {
+                result = ACTION_RESULT_SHIFT_LEFT;
+            } else {
+                possibleActions &= (~(1 << ACTION_RESULT_SHIFT_LEFT));
+            }
+        }
+
+        if (possibleActions & (1 << ACTION_RESULT_SHIFT_RIGHT)) {
+            if (joyPos == JOY_POS_CENTER) {
+                result = ACTION_RESULT_SHIFT_RIGHT;
+            } else {
+                possibleActions &= (~(1 << ACTION_RESULT_SHIFT_RIGHT));
+            }
+        }
+
+        if (possibleActions & (1 << ACTION_ADD)) {
+            if ((joyPos == JOY_POS_DOWN) &&
+                (oldJoyPos == JOY_POS_DOWN_RIGHT)) {
+                result = ACTION_ADD;
+                possibleActions = 0;
+            } else if (joyPos != oldJoyPos + 1) {
+                possibleActions &= (~(1 << ACTION_ADD));
+            }
+        } else if (possibleActions & (1 << ACTION_SUBTRACT)) {
+            if ((joyPos == JOY_POS_DOWN) &&
+                (oldJoyPos == JOY_POS_DOWN_RIGHT)) {
+                result = ACTION_SUBTRACT;
+                possibleActions = 0;
+            } else if (joyPos != oldJoyPos + 1) {
+                possibleActions &= (~(1 << ACTION_SUBTRACT));
+            }
+        }
+
+        if (joyPos == JOY_POS_CENTER) {
+            possibleActions = -1;
+        }
+    }
+
+    oldJoyPos = joyPos;
+    oldJoyState = joyState;
+    
+    return result;
+}
+
+
+void graphicalInterface(void)
+{
+    // Install drivers
+    tDigitPos pos;
+
+    joy_install(&a2e_stdjoy);
+    tgi_install(&a2e_hi);
+
+    tgi_init();
+    tgi_clear();
+    for (pos = 0; pos < NUM_OPERAND_DIGITS; pos++) {
+        drawOperand(pos);
+    }
+
+    // Mixed text and graphics mode
+    asm ("STA %w", 0xc053);
+    printf("\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n");
+    printState();
+
+    while (true) {
+        if ((kbhit()) &&
+            (cgetc() == ' ')) {
+            break;
+        }
+        switch (getNextAction()) {
+            case ACTION_NULL:
+                break;
+            case ACTION_OPERAND_SHIFT_LEFT:
+                shiftOperandPos(true);
+                break;
+
+            case ACTION_OPERAND_SHIFT_RIGHT:
+                shiftOperandPos(false);
+                break;
+
+            case ACTION_OPERAND_INC:
+                incOperandPos(selectedOperand);
+                break;
+
+            case ACTION_OPERAND_DEC:
+                decOperandPos(selectedOperand);
+                break;
+
+            case ACTION_RESULT_SHIFT_LEFT:
+                shiftResultPos(true);
+                printState();
+                break;
+
+            case ACTION_RESULT_SHIFT_RIGHT:
+                shiftResultPos(false);
+                printState();
+                break;
+
+            case ACTION_ADD:
+                crank(false);
+                printState();
+                break;
+
+            case ACTION_SUBTRACT:
+                crank(true);
+                printState();
+                break;
+
+            case ACTION_CLEAR:
+                clearDevice();
+                printState();
+                break;
+        }
+    }
+   
+    // Uninstall drivers
+    tgi_uninstall(); 
+    joy_uninstall();
+}
+
+
+int main(void)
+{
+    graphicalInterface();
+    return 0;
+}