commit 1b87ca8aa3a98600e69f14a83823e67eb90aabf7
Author: Jeremy Penner <jeremy@sporktania.com>
Date:   Sat Jan 5 16:16:08 2019 -0500

    Initial commit

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..15e50eb
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+*.obj
+*.bak
+
diff --git a/testbed.c b/testbed.c
new file mode 100755
index 0000000..1c1e90a
--- /dev/null
+++ b/testbed.c
@@ -0,0 +1,511 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <dos.h>
+
+/*** V I D E O ***/
+#define setMode(hexval) asm { mov ax, hexval; int 10h }
+
+#define setVGAMode() setMode(0013h)
+#define setEGAMode() setMode(000Dh)
+#define setTextMode() setMode(0003h)
+
+#define REG_TS   0x03c4
+#define REG_GDC  0x03ce
+#define REG_CRTC 0x03d4
+
+#define PLANE_B 0x00
+#define PLANE_G 0x01
+#define PLANE_R 0x02
+#define PLANE_I 0x03
+#define setPlane(p) outport(REG_TS, 2 | (0x100 << p))
+#define setAllPlanes() outport(REG_TS, 0x0f02)
+
+#define VID ((volatile char far *)MK_FP(0xa000, 0))
+
+void vid_cleanup() {
+  setTextMode();
+}
+
+typedef struct {
+  unsigned int b[16];
+  unsigned int g[16];
+  unsigned int r[16];
+  unsigned int i[16];
+} Tile_t;
+
+unsigned int PAGE[] = { 0x00, 0x20, 0x40, 0x60 };
+// todo: HIGH BITS??
+#define setWriteMode(m) outport(REG_GDC, 0x05 | m << 8)
+
+void prepareEgaMemCopy() {
+  setAllPlanes();
+  setWriteMode(1);
+}
+#define PAGE_STRIDE 40
+void blitTile(unsigned int offsetFrom, unsigned int offsetTo) {
+  int y;
+  for (y = 0; y < 16; y ++) {
+    VID[offsetTo] = VID[offsetFrom ++];
+    VID[offsetTo + 1] = VID[offsetFrom ++];
+    offsetTo += PAGE_STRIDE;
+  }
+}
+
+#if 0
+void blitTile(Tile_t *tile, int plane, unsigned int page, unsigned int x, unsigned int y) {
+  unsigned int *data = tile->b + (plane << 4);
+  volatile unsigned int far *out = (volatile unsigned int far *)
+    &VID[(y * 640) + (x << 1) + (page << 8)];
+  int i;
+
+  for (i = 0; i < 320; i += 20) {
+    out[i] = *(data++);
+  }
+}
+
+#endif
+
+#define flipPage(p) outport(REG_CRTC, 0x0c | (p << 8))
+
+/*** K E Y B O A R D ***/
+#define KBD_INT 0x09
+void interrupt (*oldKbdISR)() = NULL;
+
+void kbd_cleanup() {
+  if (oldKbdISR != NULL) {
+    setvect(KBD_INT, oldKbdISR);
+    oldKbdISR = NULL;
+  }
+}
+
+volatile char keybuf[128];
+volatile char kbd_triggered = 0;
+
+void interrupt kbd_isr() {
+  unsigned char raw;
+  char ctl;
+
+  asm sti;
+  raw = inp(0x60);
+  ctl = inp(0x61) | 0x82;
+  outp(0x61, ctl);
+  outp(0x61, ctl & 0x7f);
+  outp(0x20, 0x20);
+
+  if (raw & 0x80) {
+    keybuf[raw & 0x7f] = 0;
+  } else {
+    keybuf[raw] = 1;
+  }
+  kbd_triggered = raw;
+}
+
+#define K_ESC   1
+#define K_1     2
+#define K_2	3
+#define K_3	4
+#define K_4	5
+#define K_5	6
+#define K_6	7
+#define K_7	8
+#define K_8	9
+#define K_9	10
+#define K_0	11
+#define K_MINUS	12
+#define K_EQUAL	13
+#define K_BKSP	14
+#define K_TAB	15
+#define K_Q	16
+#define K_W	17
+#define K_E	18
+#define K_R	19
+#define K_T	20
+#define K_Y	21
+#define K_U	22
+#define K_I	23
+#define K_O	24
+#define K_P	25
+#define K_LBRK	26
+#define K_RBRK	27
+#define K_ENTER 28
+#define K_CTRL  29
+#define K_A	30
+#define K_S	31
+#define K_D	32
+#define K_F	33
+#define K_G	34
+#define K_H	35
+#define K_J	36
+#define K_K	37
+#define K_L	38
+#define K_SEMI	39
+#define K_APOS	40
+#define K_TILDE	41
+#define K_LSHFT 42
+#define K_BSLSH 43
+#define K_Z	44
+#define K_X	45
+#define K_C	46
+#define K_V	47
+#define K_B	48
+#define K_N	49
+#define K_M	50
+#define K_COMMA	51
+#define K_DOT	52
+#define K_SLASH	53
+#define K_RSHFT	54
+#define K_PSCRN	55
+#define K_ALT	56
+#define K_SPACE 57
+#define K_CAPS	58
+#define K_F1	59
+#define K_F2	60
+#define K_F3	61
+#define K_F4	62
+#define K_F5	63
+#define K_F6	64
+#define K_F7	65
+#define K_F8	66
+#define K_F9	67
+#define K_F10	68
+#define K_NUMLK	69
+#define K_SCRL	70
+#define K_HOME	71
+#define K_UP    72
+#define K_PGUP	73
+#define K_NDASH	74
+#define K_LEFT  75
+#define K_CENT	76
+#define K_RIGHT 77
+#define K_NPLUS	78
+#define K_END 	79
+#define K_DOWN  80
+#define K_PGDN	81
+#define K_INS	82
+#define K_DEL	83
+#define K_F11	87
+#define K_F12	88
+#define keyPressed(k) keybuf[k]
+
+unsigned char kbd_wait() {
+  kbd_triggered = 0;
+  while (!kbd_triggered) {}
+  return kbd_triggered;
+}
+
+void kbd_init() {
+  if (oldKbdISR == NULL) {
+    memset(keybuf, 0, 128);
+    oldKbdISR = getvect(KBD_INT);
+    setvect(KBD_INT, kbd_isr);
+    atexit(kbd_cleanup);
+  }
+}
+
+/*** M O U S E ***/
+struct {
+  unsigned int x;
+  unsigned int y;
+  unsigned int buttons;
+} MOUSE;
+
+void far mouse_callback() {
+  asm {
+    mov ax, DGROUP
+    mov ds, ax
+    shr cx, 1
+    mov MOUSE.x, cx
+    mov MOUSE.y, dx
+    mov MOUSE.buttons, bx
+  }
+}
+
+void mouse_cleanup() {
+  //uninstall handler
+  asm {
+    mov ax, 0ch
+    mov dx, 0
+    mov es, dx
+    mov cx, 0
+    int 33h
+
+    xor ax, ax
+    int 33h
+  }
+}
+
+void mouse_init() {
+  unsigned seg_mouse_callback = FP_SEG(mouse_callback);
+  unsigned off_mouse_callback = FP_OFF(mouse_callback);
+  unsigned int result;
+  asm {
+    xor ax, ax
+    int 33h
+    mov result, ax
+  }
+  if (result == 0) {
+    printf("Mouse driver not installed\n");
+    exit(1);
+  }
+  atexit(mouse_cleanup);
+
+  asm {
+    mov ax, seg_mouse_callback
+    mov es, ax
+    mov dx, off_mouse_callback
+    mov ax, 0ch
+    mov cx, 1fh
+    int 33h
+  }
+}
+
+#define mouse_hide() asm { mov ax, 02h; int 33h }
+#define mouse_show() asm { mov ax, 01h; int 33h }
+
+/*** T I F F ***/
+typedef struct {
+  unsigned int endian;
+  unsigned int version;
+  unsigned long ifdOffset;
+} TifHeader_t;
+
+#define TIF_WIDTH 256
+#define TIF_HEIGHT 257
+#define TIF_BITSPERSAMPLE 258
+#define TIF_COMPRESSION 259
+#define TIF_STRIPOFFSETS 273
+#define TIF_ROWSPERSTRIP 278
+
+typedef struct {
+  unsigned int id;
+  unsigned int dataType;
+  unsigned long dataCount;
+  unsigned long dataOffset;
+} TifTag_t;
+
+typedef struct {
+  unsigned int width;
+  unsigned int height;
+  unsigned long rowsPerStrip;
+  unsigned long stripCount;
+  unsigned long stripOffsets;
+} TifImageMeta_t;
+
+TifImageMeta_t tifLoadMeta(FILE *f) {
+  TifImageMeta_t meta = {0, 0, 0, 0, 0};
+  TifHeader_t header;
+  TifTag_t tag;
+  unsigned int i, tagCount;
+
+  fseek(f, 0, SEEK_SET);
+  fread(&header, 8, 1, f);
+
+  if (header.endian != 0x4949 || header.version != 0x2a) {
+    goto fail;
+  }
+  fseek(f, header.ifdOffset, SEEK_SET);
+  fread(&tagCount, 2, 1, f);
+  for (i = 0; i < tagCount; i ++) {
+    fread(&tag, 12, 1, f);
+    if (tag.id == TIF_WIDTH) {
+      meta.width = tag.dataOffset;
+    } else if (tag.id == TIF_HEIGHT) {
+      meta.height = tag.dataOffset;
+    } else if (tag.id == TIF_BITSPERSAMPLE) {
+      if (tag.dataOffset != 4) goto fail;
+    } else if (tag.id == TIF_COMPRESSION) {
+      if (tag.dataOffset != 1) goto fail;
+    } else if (tag.id == TIF_STRIPOFFSETS) {
+      meta.stripCount = tag.dataCount;
+      meta.stripOffsets = tag.dataOffset;
+    } else if (tag.id == TIF_ROWSPERSTRIP) {
+      meta.rowsPerStrip = tag.dataOffset;
+    }
+  }
+  return meta;
+fail:
+  meta.stripCount = 0;
+  return meta;
+}
+
+#define MAX_WIDTH 320
+
+int tifLoadEGA(FILE *f, TifImageMeta_t meta, unsigned int vidOffset, int maxY) {
+  int istrip;
+  int irow;
+  int ipixelpair;
+  int y = 0;
+  unsigned long offset;
+  unsigned char rowData[MAX_WIDTH >> 1];
+  volatile unsigned char far *out = &VID[vidOffset];
+  unsigned char b, g, r, i;
+
+  if (meta.width > MAX_WIDTH || (meta.width % 16) != 0) {
+    return 0;
+  }
+  setWriteMode(0);
+
+  for (istrip = 0; istrip < meta.stripCount; istrip ++) {
+    fseek(f, meta.stripOffsets + (istrip << 2), SEEK_SET);
+    fread(&offset, 4, 1, f);
+    fseek(f, offset, SEEK_SET);
+
+    for (irow = 0; irow < meta.rowsPerStrip; irow ++) {
+      int ipixelpairLim = meta.width >> 1;
+      fread(rowData, 1, ipixelpairLim, f);
+      b = g = r = i = 0;
+      for (ipixelpair = 0; ipixelpair < ipixelpairLim; ipixelpair ++) {
+	unsigned char pixelpair = rowData[ipixelpair];
+	int bpair = (pixelpair & 0x01) | (pixelpair & 0x10) >> 3;
+	int gpair = (pixelpair & 0x02) >> 1 | (pixelpair & 0x20) >> 4;
+	int rpair = (pixelpair & 0x04) >> 2 | (pixelpair & 0x40) >> 5;
+	int ipair = (pixelpair & 0x08) >> 3 | (pixelpair & 0x80) >> 6;
+	int shift = (ipixelpair % 4) << 1;
+
+	b |= bpair << shift;
+	g |= gpair << shift;
+	r |= rpair << shift;
+	i |= ipair << shift;
+
+	if (shift == 6 || ipixelpair == ipixelpairLim - 1) {
+	  // todo: use write mode 2, this is slooww
+	  setPlane(PLANE_B); *out = b;
+	  setPlane(PLANE_R); *out = r;
+	  setPlane(PLANE_G); *out = g;
+	  setPlane(PLANE_I); *out = i;
+	  out ++;
+	  b = g = r = i = 0;
+	}
+      }
+      y++;
+      if (y == maxY) {
+	return y;
+      }
+    }
+  }
+  return y;
+}
+
+int tifLoad(FILE *f, TifImageMeta_t meta, unsigned int *planeBuf, int maxY, int yRepeat) {
+  int istrip;
+  int irow;
+  int ipixelpair;
+  int y = 0;
+  unsigned long offset;
+  unsigned char rowData[MAX_WIDTH >> 1];
+  unsigned int planeStride = (meta.width >> 4) * yRepeat;
+  unsigned int *b = planeBuf - 1;
+  unsigned int *g = b + planeStride;
+  unsigned int *r = g + planeStride;
+  unsigned int *i = r + planeStride;
+
+  if (meta.width > MAX_WIDTH || (meta.width % 16) != 0) {
+    return 0;
+  }
+
+  for (istrip = 0; istrip < meta.stripCount; istrip ++) {
+    fseek(f, meta.stripOffsets + (istrip << 2), SEEK_SET);
+    fread(&offset, 4, 1, f);
+    fseek(f, offset, SEEK_SET);
+
+    for (irow = 0; irow < meta.rowsPerStrip; irow ++) {
+      fread(rowData, 1, meta.width >> 1, f);
+      for (ipixelpair = 0; ipixelpair < meta.width >> 1; ipixelpair ++) {
+	unsigned char pixelpair = rowData[ipixelpair];
+	int bpair = (pixelpair & 0x01) | (pixelpair & 0x10) >> 3;
+	int gpair = (pixelpair & 0x02) >> 1 | (pixelpair & 0x20) >> 4;
+	int rpair = (pixelpair & 0x04) >> 2 | (pixelpair & 0x40) >> 5;
+	int ipair = (pixelpair & 0x08) >> 3 | (pixelpair & 0x80) >> 6;
+	int shift = (ipixelpair % 8) << 1;
+	if (shift == 0) {
+	  *++b = bpair;
+	  *++g = gpair;
+	  *++r = rpair;
+	  *++i = ipair;
+	} else {
+	  *b |= bpair << shift;
+	  *g |= gpair << shift;
+	  *r |= rpair << shift;
+	  *i |= ipair << shift;
+	}
+      }
+      y++;
+      if (y == maxY) {
+	return y;
+      }
+      if (y % yRepeat == 0) {
+	b += planeStride * 3;
+	g += planeStride * 3;
+	r += planeStride * 3;
+	i += planeStride * 3;
+      }
+    }
+  }
+  return y;
+}
+
+/*** S C R A T C H ***/
+void paintPattern(int r, int g, int b, int t) {
+  int i;
+
+  setPlane(PLANE_R);
+  for (i = 0; i < 8000; i ++) {
+    VID[i] = r;
+  }
+  setPlane(PLANE_G);
+  for (i = 0; i < 8000; i ++) {
+    VID[i] = g;
+  }
+  setPlane(PLANE_B);
+  for (i = 0; i < 8000; i ++) {
+    VID[i] = b;
+  }
+  setPlane(PLANE_I);
+  for (i = 0; i < 8000; i ++) {
+    VID[i] = t;
+  }
+}
+
+int main() {
+  Tile_t tiles[16];
+  FILE *f;
+  TifImageMeta_t meta;
+  int plane;
+  int x;
+  int y;
+  int z = 0;
+  unsigned int drawOffset;
+  unsigned int page = 0;
+
+  #define OFF_TILES 0x4200
+  setEGAMode();
+
+  f = fopen("TILES.TIF", "rb");
+  meta = tifLoadMeta(f);
+  tifLoadEGA(f, meta, OFF_TILES, 256);
+  fclose(f);
+
+  mouse_init();
+  kbd_init();
+  atexit(vid_cleanup);
+
+  while (!keyPressed(K_ESC)) {
+    page ^= 0x20;
+
+    prepareEgaMemCopy();
+    drawOffset = page << 8;
+    for (y = 0; y < 13; y ++) {
+      for (x = 0; x < 20; x ++) {
+	blitTile(OFF_TILES + ((((x + y + z) >> 2) % 3) << 5), drawOffset);
+	drawOffset += 2;
+      }
+      drawOffset += 600; // 40 bytes per line * 15 more lines
+    }
+    flipPage(page);
+
+    kbd_wait();
+    z++;
+  }
+
+  return 0;
+}
diff --git a/testbed.exe b/testbed.exe
new file mode 100755
index 0000000..8910cb9
Binary files /dev/null and b/testbed.exe differ
diff --git a/tiles.tif b/tiles.tif
new file mode 100755
index 0000000..2e2f5df
Binary files /dev/null and b/tiles.tif differ