diff --git a/src/blit.c b/src/blit.c
new file mode 100644
index 000000000..16f76918e
--- /dev/null
+++ b/src/blit.c
@@ -0,0 +1,211 @@
+#include "global.h"
+
+// this file's functions
+void BlitBitmapRect4Bit(struct Bitmap *src, struct Bitmap *dst, u16 srcX, u16 srcY, u16 dstX, u16 dstY, u16 width, u16 height, u8 colorKey);
+
+void BlitBitmapRect4BitWithoutColorKey(struct Bitmap *src, struct Bitmap *dst, u16 srcX, u16 srcY, u16 dstX, u16 dstY, u16 width, u16 height)
+{
+    BlitBitmapRect4Bit(src, dst, srcX, srcY, dstX, dstY, width, height, 0xFF);
+}
+
+void BlitBitmapRect4Bit(struct Bitmap *src, struct Bitmap *dst, u16 srcX, u16 srcY, u16 dstX, u16 dstY, u16 width, u16 height, u8 colorKey)
+{
+    s32 xEnd;
+    s32 yEnd;
+    s32 multiplierSrcY;
+    s32 multiplierDstY;
+    s32 loopSrcY, loopDstY;
+    s32 loopSrcX, loopDstX;
+    u8 *pixelsSrc;
+    u8 *pixelsDst;
+    s32 toOrr;
+    s32 toAnd;
+    s32 toShift;
+
+    if (dst->width - dstX < width)
+        xEnd = (dst->width - dstX) + srcX;
+    else
+        xEnd = srcX + width;
+
+    if (dst->height - dstY < height)
+        yEnd = (dst->height - dstY) + srcY;
+    else
+        yEnd = height + srcY;
+
+    multiplierSrcY = (src->width + (src->width & 7)) >> 3;
+    multiplierDstY = (dst->width + (dst->width & 7)) >> 3;
+
+    if (colorKey == 0xFF)
+    {
+        for (loopSrcY = srcY, loopDstY = dstY; loopSrcY < yEnd; loopSrcY++, loopDstY++)
+        {
+            for (loopSrcX = srcX, loopDstX = dstX; loopSrcX < xEnd; loopSrcX++, loopDstX++)
+            {
+                pixelsSrc = src->pixels + ((loopSrcX >> 1) & 3) + ((loopSrcX >> 3) << 5) + (((loopSrcY >> 3) * multiplierSrcY) << 5) + ((u32)(loopSrcY << 0x1d) >> 0x1B);
+                pixelsDst = dst->pixels + ((loopDstX >> 1) & 3) + ((loopDstX >> 3) << 5) + (((loopDstY >> 3) * multiplierDstY) << 5) + ((u32)(loopDstY << 0x1d) >> 0x1B);
+                toOrr = ((*pixelsSrc >> ((loopSrcX & 1) << 2)) & 0xF);
+                toShift = ((loopDstX & 1) << 2);
+                toOrr <<= toShift;
+                toAnd = 0xF0 >> (toShift);
+                *pixelsDst = toOrr | (*pixelsDst & toAnd);
+            }
+        }
+    }
+    else
+    {
+        for (loopSrcY = srcY, loopDstY = dstY; loopSrcY < yEnd; loopSrcY++, loopDstY++)
+        {
+            for (loopSrcX = srcX, loopDstX = dstX; loopSrcX < xEnd; loopSrcX++, loopDstX++)
+            {
+                pixelsSrc = src->pixels + ((loopSrcX >> 1) & 3) + ((loopSrcX >> 3) << 5) + (((loopSrcY >> 3) * multiplierSrcY) << 5) + ((u32)(loopSrcY << 0x1d) >> 0x1B);
+                pixelsDst = dst->pixels + ((loopDstX >> 1) & 3) + ((loopDstX >> 3) << 5) + (((loopDstY >> 3) * multiplierDstY) << 5) + ((u32)(loopDstY << 0x1d) >> 0x1B);
+                toOrr = ((*pixelsSrc >> ((loopSrcX & 1) << 2)) & 0xF);
+                if (toOrr != colorKey)
+                {
+                    toShift = ((loopDstX & 1) << 2);
+                    toOrr <<= toShift;
+                    toAnd = 0xF0 >> (toShift);
+                    *pixelsDst = toOrr | (*pixelsDst & toAnd);
+                }
+            }
+        }
+    }
+}
+
+void FillBitmapRect4Bit(struct Bitmap *surface, u16 x, u16 y, u16 width, u16 height, u8 fillValue)
+{
+    s32 xEnd;
+    s32 yEnd;
+    s32 multiplierY;
+    s32 loopX, loopY;
+    s32 toOrr1, toOrr2;
+
+    xEnd = x + width;
+    if (xEnd > surface->width)
+        xEnd = surface->width;
+
+    yEnd = y + height;
+    if (yEnd > surface->height)
+        yEnd = surface->height;
+
+    multiplierY = (surface->width + (surface->width & 7)) >> 3;
+    toOrr1 = (u32)(fillValue << 0x1C) >> 0x18;
+    toOrr2 = (fillValue & 0xF);
+
+    for (loopY = y; loopY < yEnd; loopY++)
+    {
+        for (loopX = x; loopX < xEnd; loopX++)
+        {
+            u8 *pixels = surface->pixels + ((loopX >> 1) & 3) + ((loopX >> 3) << 5) + (((loopY >> 3) * multiplierY) << 5) + ((u32)(loopY << 0x1d) >> 0x1B);
+            if ((loopX << 0x1F) != 0)
+                *pixels = toOrr1 | (*pixels & 0xF);
+            else
+                *pixels = toOrr2 | (*pixels & 0xF0);
+        }
+    }
+}
+
+void BlitBitmapRect4BitTo8Bit(struct Bitmap *src, struct Bitmap *dst, u16 srcX, u16 srcY, u16 dstX, u16 dstY, u16 width, u16 height, u8 colorKey, u8 paletteOffset)
+{
+    s32 palOffsetBits;
+    s32 xEnd;
+    s32 yEnd;
+    s32 multiplierSrcY;
+    s32 multiplierDstY;
+    s32 loopSrcY, loopDstY;
+    s32 loopSrcX, loopDstX;
+    u8 *pixelsSrc;
+    u8 *pixelsDst;
+    s32 colorKeyBits;
+
+    palOffsetBits = (u32)(paletteOffset << 0x1C) >> 0x18;
+    colorKeyBits = (u32)(colorKey << 0x1C) >> 0x18;
+
+    if (dst->width - dstX < width)
+        xEnd = (dst->width - dstX) + srcX;
+    else
+        xEnd = width + srcX;
+
+    if (dst->height - dstY < height)
+        yEnd = (srcY + dst->height) - dstY;
+    else
+        yEnd = srcY + height;
+
+    multiplierSrcY = (src->width + (src->width & 7)) >> 3;
+    multiplierDstY = (dst->width + (dst->width & 7)) >> 3;
+
+    if (colorKey == 0xFF)
+    {
+        for (loopSrcY = srcY, loopDstY = dstY; loopSrcY < yEnd; loopSrcY++, loopDstY++)
+        {
+            pixelsSrc = src->pixels + ((srcX >> 1) & 3) + ((srcX >> 3) << 5) + (((loopSrcY >> 3) * multiplierSrcY) << 5) + ((u32)(loopSrcY << 0x1d) >> 0x1b);
+            for (loopSrcX = srcX, loopDstX = dstX; loopSrcX < xEnd; loopSrcX++, loopDstX++)
+            {
+                pixelsDst = dst->pixels + (loopDstX & 7) + ((loopDstX >> 3) << 6) + (((loopDstY >> 3) * multiplierDstY) << 6) + ((u32)(loopDstY << 0x1d) >> 0x1a);
+                if (loopSrcX & 1)
+                {
+                    *pixelsDst = palOffsetBits + (*pixelsSrc >> 4);
+                }
+                else
+                {
+                    pixelsSrc = src->pixels + ((loopSrcX >> 1) & 3) + ((loopSrcX >> 3) << 5) + (((loopSrcY >> 3) * multiplierSrcY) << 5) + ((u32)(loopSrcY << 0x1d) >> 0x1b);
+                    *pixelsDst = palOffsetBits + (*pixelsSrc & 0xF);
+                }
+            }
+        }
+    }
+    else
+    {
+        for (loopSrcY = srcY, loopDstY = dstY; loopSrcY < yEnd; loopSrcY++, loopDstY++)
+        {
+            pixelsSrc = src->pixels + ((srcX >> 1) & 3) + ((srcX >> 3) << 5) + (((loopSrcY >> 3) * multiplierSrcY) << 5) + ((u32)(loopSrcY << 0x1d) >> 0x1b);
+            for (loopSrcX = srcX, loopDstX = dstX; loopSrcX < xEnd; loopSrcX++, loopDstX++)
+            {
+                if (loopSrcX & 1)
+                {
+                    if ((*pixelsSrc & 0xF0) != colorKeyBits)
+                    {
+                        pixelsDst = dst->pixels + (loopDstX & 7) + ((loopDstX >> 3) << 6) + (((loopDstY >> 3) * multiplierDstY) << 6) + ((u32)(loopDstY << 0x1d) >> 0x1a);
+                        *pixelsDst = palOffsetBits + (*pixelsSrc >> 4);
+                    }
+                }
+                else
+                {
+                    pixelsSrc = src->pixels + ((loopSrcX >> 1) & 3) + ((loopSrcX >> 3) << 5) + (((loopSrcY >> 3) * multiplierSrcY) << 5) + ((u32)(loopSrcY << 0x1d) >> 0x1b);
+                    if ((*pixelsSrc & 0xF) != colorKey)
+                    {
+                        pixelsDst = dst->pixels + (loopDstX & 7) + ((loopDstX >> 3) << 6) + (((loopDstY >> 3) * multiplierDstY) << 6) + ((u32)(loopDstY << 0x1d) >> 0x1a);
+                        *pixelsDst = palOffsetBits + (*pixelsSrc & 0xF);
+                    }
+                }
+            }
+        }
+    }
+}
+
+void FillBitmapRect8Bit(struct Bitmap *surface, u16 x, u16 y, u16 width, u16 height, u8 fillValue)
+{
+    s32 xEnd;
+    s32 yEnd;
+    s32 multiplierY;
+    s32 loopX, loopY;
+
+    xEnd = x + width;
+    if (xEnd > surface->width)
+        xEnd = surface->width;
+
+    yEnd = y + height;
+    if (yEnd > surface->height)
+        yEnd = surface->height;
+
+    multiplierY = (surface->width + (surface->width & 7)) >> 3;
+
+    for (loopY = y; loopY < yEnd; loopY++)
+    {
+        for (loopX = x; loopX < xEnd; loopX++)
+        {
+            u8 *pixels = surface->pixels + (loopX & 7) + ((loopX >> 3) << 6) + (((loopY >> 3) * multiplierY) << 6) + ((u32)(loopY << 0x1d) >> 0x1a);
+            *pixels = fillValue;
+        }
+    }
+}