Add PNG decompressor in SIM

sim/inflate.ts

@@ -0,0 +1,375 @@
+// adapted from https://github.com/devongovett/tiny-inflate
+// License: MIT
+
+namespace tinf {
+
+    var TINF_OK = 0;
+    var TINF_DATA_ERROR = -3;
+
+    class Tree {
+        table = new Uint16Array(16);   /* table of code length counts */
+        trans = new Uint16Array(288);  /* code -> symbol translation table */
+    }
+
+    class Data {
+        sourceIndex = 0;
+        tag = 0;
+        bitcount = 0;
+
+        destLen = 0;
+
+        ltree = new Tree();  /* dynamic length/symbol tree */
+        dtree = new Tree();  /* dynamic distance tree */
+
+        constructor(public source: Uint8Array, public dest: Uint8Array) {
+        }
+    }
+
+    /* --------------------------------------------------- *
+     * -- uninitialized global data (static structures) -- *
+     * --------------------------------------------------- */
+
+    var sltree = new Tree();
+    var sdtree = new Tree();
+
+    /* extra bits and base tables for length codes */
+    var length_bits = new Uint8Array(30);
+    var length_base = new Uint16Array(30);
+
+    /* extra bits and base tables for distance codes */
+    var dist_bits = new Uint8Array(30);
+    var dist_base = new Uint16Array(30);
+
+    /* special ordering of code length codes */
+    var clcidx = new Uint8Array([
+        16, 17, 18, 0, 8, 7, 9, 6,
+        10, 5, 11, 4, 12, 3, 13, 2,
+        14, 1, 15
+    ]);
+
+    /* used by tinf_decode_trees, avoids allocations every call */
+    var code_tree = new Tree();
+    var lengths = new Uint8Array(288 + 32);
+
+    /* ----------------------- *
+     * -- utility functions -- *
+     * ----------------------- */
+
+    /* build extra bits and base tables */
+    function tinf_build_bits_base(bits: Uint8Array, base: Uint16Array, delta: number, first: number) {
+        /* build bits table */
+        for (let i = 0; i < delta; ++i) bits[i] = 0;
+        for (let i = 0; i < 30 - delta; ++i) bits[i + delta] = i / delta | 0;
+
+        /* build base table */
+        for (let sum = first, i = 0; i < 30; ++i) {
+            base[i] = sum;
+            sum += 1 << bits[i];
+        }
+    }
+
+    /* build the fixed huffman trees */
+    function tinf_build_fixed_trees(lt: Tree, dt: Tree) {
+        let i = 0;
+
+        /* build fixed length tree */
+        for (i = 0; i < 7; ++i) lt.table[i] = 0;
+
+        lt.table[7] = 24;
+        lt.table[8] = 152;
+        lt.table[9] = 112;
+
+        for (i = 0; i < 24; ++i) lt.trans[i] = 256 + i;
+        for (i = 0; i < 144; ++i) lt.trans[24 + i] = i;
+        for (i = 0; i < 8; ++i) lt.trans[24 + 144 + i] = 280 + i;
+        for (i = 0; i < 112; ++i) lt.trans[24 + 144 + 8 + i] = 144 + i;
+
+        /* build fixed distance tree */
+        for (i = 0; i < 5; ++i) dt.table[i] = 0;
+
+        dt.table[5] = 32;
+
+        for (i = 0; i < 32; ++i) dt.trans[i] = i;
+    }
+
+    /* given an array of code lengths, build a tree */
+    var offs = new Uint16Array(16);
+
+    function tinf_build_tree(t: Tree, lengths: Uint8Array, off: number, num: number) {
+        var i = 0, sum = 0;
+
+        /* clear code length count table */
+        for (i = 0; i < 16; ++i) t.table[i] = 0;
+
+        /* scan symbol lengths, and sum code length counts */
+        for (i = 0; i < num; ++i) t.table[lengths[off + i]]++;
+
+        t.table[0] = 0;
+
+        /* compute offset table for distribution sort */
+        for (sum = 0, i = 0; i < 16; ++i) {
+            offs[i] = sum;
+            sum += t.table[i];
+        }
+
+        /* create code->symbol translation table (symbols sorted by code) */
+        for (i = 0; i < num; ++i) {
+            if (lengths[off + i]) t.trans[offs[lengths[off + i]]++] = i;
+        }
+    }
+
+    /* ---------------------- *
+     * -- decode functions -- *
+     * ---------------------- */
+
+    /* get one bit from source stream */
+    function tinf_getbit(d: Data) {
+        /* check if tag is empty */
+        if (!d.bitcount--) {
+            /* load next tag */
+            d.tag = d.source[d.sourceIndex++];
+            d.bitcount = 7;
+        }
+
+        /* shift bit out of tag */
+        var bit = d.tag & 1;
+        d.tag >>>= 1;
+
+        return bit;
+    }
+
+    /* read a num bit value from a stream and add base */
+    function tinf_read_bits(d: Data, num: number, base: number) {
+        if (!num)
+            return base;
+
+        while (d.bitcount < 24) {
+            d.tag |= d.source[d.sourceIndex++] << d.bitcount;
+            d.bitcount += 8;
+        }
+
+        var val = d.tag & (0xffff >>> (16 - num));
+        d.tag >>>= num;
+        d.bitcount -= num;
+        return val + base;
+    }
+
+    /* given a data stream and a tree, decode a symbol */
+    function tinf_decode_symbol(d: Data, t: Tree) {
+        while (d.bitcount < 24) {
+            d.tag |= d.source[d.sourceIndex++] << d.bitcount;
+            d.bitcount += 8;
+        }
+
+        var sum = 0, cur = 0, len = 0;
+        var tag = d.tag;
+
+        /* get more bits while code value is above sum */
+        do {
+            cur = 2 * cur + (tag & 1);
+            tag >>>= 1;
+            ++len;
+
+            sum += t.table[len];
+            cur -= t.table[len];
+        } while (cur >= 0);
+
+        d.tag = tag;
+        d.bitcount -= len;
+
+        return t.trans[sum + cur];
+    }
+
+    /* given a data stream, decode dynamic trees from it */
+    function tinf_decode_trees(d: Data, lt: Tree, dt: Tree) {
+        var i = 0, num = 0, length = 0;
+
+        /* get 5 bits HLIT (257-286) */
+        let hlit = tinf_read_bits(d, 5, 257);
+
+        /* get 5 bits HDIST (1-32) */
+        let hdist = tinf_read_bits(d, 5, 1);
+
+        /* get 4 bits HCLEN (4-19) */
+        let hclen = tinf_read_bits(d, 4, 4);
+
+        for (i = 0; i < 19; ++i) lengths[i] = 0;
+
+        /* read code lengths for code length alphabet */
+        for (i = 0; i < hclen; ++i) {
+            /* get 3 bits code length (0-7) */
+            var clen = tinf_read_bits(d, 3, 0);
+            lengths[clcidx[i]] = clen;
+        }
+
+        /* build code length tree */
+        tinf_build_tree(code_tree, lengths, 0, 19);
+
+        /* decode code lengths for the dynamic trees */
+        for (num = 0; num < hlit + hdist;) {
+            var sym = tinf_decode_symbol(d, code_tree);
+
+            switch (sym) {
+                case 16:
+                    /* copy previous code length 3-6 times (read 2 bits) */
+                    var prev = lengths[num - 1];
+                    for (length = tinf_read_bits(d, 2, 3); length; --length) {
+                        lengths[num++] = prev;
+                    }
+                    break;
+                case 17:
+                    /* repeat code length 0 for 3-10 times (read 3 bits) */
+                    for (length = tinf_read_bits(d, 3, 3); length; --length) {
+                        lengths[num++] = 0;
+                    }
+                    break;
+                case 18:
+                    /* repeat code length 0 for 11-138 times (read 7 bits) */
+                    for (length = tinf_read_bits(d, 7, 11); length; --length) {
+                        lengths[num++] = 0;
+                    }
+                    break;
+                default:
+                    /* values 0-15 represent the actual code lengths */
+                    lengths[num++] = sym;
+                    break;
+            }
+        }
+
+        /* build dynamic trees */
+        tinf_build_tree(lt, lengths, 0, hlit);
+        tinf_build_tree(dt, lengths, hlit, hdist);
+    }
+
+    /* ----------------------------- *
+     * -- block inflate functions -- *
+     * ----------------------------- */
+
+    /* given a stream and two trees, inflate a block of data */
+    function tinf_inflate_block_data(d: Data, lt: Tree, dt: Tree) {
+        while (true) {
+            var sym = tinf_decode_symbol(d, lt);
+
+            /* check for end of block */
+            if (sym === 256) {
+                return TINF_OK;
+            }
+
+            if (sym < 256) {
+                d.dest[d.destLen++] = sym;
+            } else {
+                sym -= 257;
+
+                /* possibly get more bits from length code */
+                let length = tinf_read_bits(d, length_bits[sym], length_base[sym]);
+
+                let dist = tinf_decode_symbol(d, dt);
+
+                /* possibly get more bits from distance code */
+                let offs = d.destLen - tinf_read_bits(d, dist_bits[dist], dist_base[dist]);
+
+                /* copy match */
+                for (let i = offs; i < offs + length; ++i) {
+                    d.dest[d.destLen++] = d.dest[i];
+                }
+            }
+        }
+    }
+
+    /* inflate an uncompressed block of data */
+    function tinf_inflate_uncompressed_block(d: Data) {
+        /* unread from bitbuffer */
+        while (d.bitcount > 8) {
+            d.sourceIndex--;
+            d.bitcount -= 8;
+        }
+
+        /* get length */
+        let length = d.source[d.sourceIndex + 1];
+        length = 256 * length + d.source[d.sourceIndex];
+
+        /* get one's complement of length */
+        let invlength = d.source[d.sourceIndex + 3];
+        invlength = 256 * invlength + d.source[d.sourceIndex + 2];
+
+        /* check length */
+        if (length !== (~invlength & 0x0000ffff))
+            return TINF_DATA_ERROR;
+
+        d.sourceIndex += 4;
+
+        /* copy block */
+        for (let i = length; i; --i)
+            d.dest[d.destLen++] = d.source[d.sourceIndex++];
+
+        /* make sure we start next block on a byte boundary */
+        d.bitcount = 0;
+
+        return TINF_OK;
+    }
+
+    /* inflate stream from source to dest */
+    export function uncompress(source: Uint8Array, dest: Uint8Array) {
+        var d = new Data(source, dest);
+        var bfinal = 0, res = 0;
+
+        do {
+            /* read final block flag */
+            bfinal = tinf_getbit(d);
+
+            /* read block type (2 bits) */
+            let btype = tinf_read_bits(d, 2, 0);
+
+            /* decompress block */
+            switch (btype) {
+                case 0:
+                    /* decompress uncompressed block */
+                    res = tinf_inflate_uncompressed_block(d);
+                    break;
+                case 1:
+                    /* decompress block with fixed huffman trees */
+                    res = tinf_inflate_block_data(d, sltree, sdtree);
+                    break;
+                case 2:
+                    /* decompress block with dynamic huffman trees */
+                    tinf_decode_trees(d, d.ltree, d.dtree);
+                    res = tinf_inflate_block_data(d, d.ltree, d.dtree);
+                    break;
+                default:
+                    res = TINF_DATA_ERROR;
+            }
+
+            if (res !== TINF_OK)
+                throw new Error('Data error');
+
+        } while (!bfinal);
+
+        if (d.destLen >= d.dest.length)
+            return null
+
+        if (d.destLen < d.dest.length) {
+            if (typeof d.dest.slice === 'function')
+                return d.dest.slice(0, d.destLen);
+            else
+                return d.dest.subarray(0, d.destLen);
+        }
+
+        return d.dest;
+    }
+
+    /* -------------------- *
+     * -- initialization -- *
+     * -------------------- */
+
+    /* build fixed huffman trees */
+    tinf_build_fixed_trees(sltree, sdtree);
+
+    /* build extra bits and base tables */
+    tinf_build_bits_base(length_bits, length_base, 4, 3);
+    tinf_build_bits_base(dist_bits, dist_base, 2, 1);
+
+    /* fix a special case */
+    length_bits[28] = 0;
+    length_base[28] = 258;
+
+}

sim/state/screen.ts

@@ -90,36 +90,172 @@ namespace pxsim.screen {
         screenState.blitLineCore(XX(xw), y, YY(xw), buf, mode)
     }
 
+    export function isValidImage(buf: RefBuffer) {
+        return buf.data.length >= 3 && buf.data[0] == 0xf0;
+    }
+
+    export function PIX2BYTES(x: number) {
+        return ((x + 7) >> 3)
+    }
+    export function clear(): void {
+        const screenState = (board() as DalBoard).screenState;
+        screenState.clear()
+    }
+
+    export function dump() {
+        // No need for this one.
+    }
+
+    export function imageOf(buf: RefBuffer) {
+        return incr(buf)
+    }
+}
+
+namespace pxsim.screen {
+    function DMESG(msg: string) {
+        control.dmesg(msg)
+    }
+    const NULL: RefBuffer = null;
+    function revbits(v: number) {
+        v = (v & 0xf0) >> 4 | (v & 0x0f) << 4;
+        v = (v & 0xcc) >> 2 | (v & 0x33) << 2;
+        v = (v & 0xaa) >> 1 | (v & 0x55) << 1;
+        return v;
+    }
+
+    export function unpackPNG(png: RefBuffer) {
+        function memcmp(off: number, mark: string) {
+            for (let i = 0; i < mark.length; ++i) {
+                if (mark.charCodeAt(i) != png.data[off + i])
+                    return 1
+            }
+            return 0
+        }
+        function readInt(off: number) {
+            return ((png.data[off] << 24) | (png.data[off + 1] << 16) |
+                (png.data[off + 2] << 8) | (png.data[off + 3])) >>> 0
+        }
+        if (!png) {
+            DMESG("PNG: Missing image");
+            return NULL;
+        }
+        if (png.data.length < 45) {
+            DMESG("PNG: File too small");
+            return NULL;
+        }
+
+        if (memcmp(0, "\x89PNG\r\n\x1A\n") != 0) {
+            DMESG("PNG: Invalid header");
+            return NULL;
+        }
+
+        if (memcmp(12, "IHDR") != 0) {
+            DMESG("PNG: missing IHDR");
+            return NULL;
+        }
+
+        const lenIHDR = readInt(8);
+        const width = readInt(16);
+        const height = readInt(20);
+        const lenIDAT = readInt(33);
+        const sizeOfHD = 41;
+
+        if (lenIHDR != 13) {
+            DMESG("PNG: bad IHDR len");
+            return NULL;
+        }
+        if (memcmp(24, "\x01\x00\x00\x00\x00") != 0) {
+            DMESG("PNG: not 1-bit grayscale");
+            return NULL;
+        }
+        if (memcmp(37, "IDAT") != 0) {
+            DMESG("PNG: missing IDAT");
+            return NULL;
+        }
+        if (lenIDAT + sizeOfHD >= png.data.length) {
+            DMESG("PNG: buffer too short");
+            return NULL;
+        }
+        if (width > 300 || height > 300) {
+            DMESG("PNG: too big");
+            return NULL;
+        }
+
+        const byteW = (width + 7) >> 3;
+        const sz = (byteW + 1) * height;
+        const tmp = new Uint8Array(sz + 1);
+        // uncompress doesn't take the zlib header, hence + 2
+        const two = tinf.uncompress(png.data.slice(sizeOfHD + 2, sizeOfHD + lenIDAT), tmp);
+        if (two.length != sz) {
+            DMESG("PNG: invalid compressed size");
+            return NULL;
+        }
+
+        const res = output.createBuffer(2 + byteW * height);
+        res.data[0] = 0xf0;
+        res.data[1] = width;
+        let dst = 2
+        let src = 0
+        let lastMask = (1 << (width & 7)) - 1;
+        if (lastMask == 0)
+            lastMask = 0xff;
+        for (let i = 0; i < height; ++i) {
+            if (two[src++] != 0) {
+                DMESG("PNG: unsupported filter");
+                decr(res);
+                return NULL;
+            }
+            for (let j = 0; j < byteW; ++j) {
+                res.data[dst] = ~revbits(two[src++]);
+                if (j == byteW - 1) {
+                    res.data[dst] &= lastMask;
+                }
+                dst++;
+            }
+        }
+        return res;
+    }
+}
+
+namespace pxsim.ImageMethods {
     const bitdouble = [
         0x00, 0x03, 0x0c, 0x0f, 0x30, 0x33, 0x3c, 0x3f, 0xc0, 0xc3, 0xcc, 0xcf, 0xf0, 0xf3, 0xfc, 0xff,
     ]
 
-    export function isValidIcon(buf: RefBuffer) {
+    export function buffer(buf: RefBuffer) {
-        return buf.data.length >= 3 && buf.data[0] == 0xf0;
+        return incr(buf)
     }
 
-    function PIX2BYTES(x: number) {
+    export function width(buf: RefBuffer) {
-        return ((x + 7) >> 3)
+        if (!screen.isValidImage(buf)) return 0
+        return buf.data[1]
     }
 
-    export function drawIcon(x: number, y: number, buf: RefBuffer, mode: Draw): void {
+    export function height(buf: RefBuffer) {
+        if (!screen.isValidImage(buf)) return 0
+        const bw = screen.PIX2BYTES(buf.data[1]);
+        const h = ((buf.data.length - 2) / bw) | 0;
+        return h
+    }
+
+    export function draw(buf: RefBuffer, x: number, y: number, mode: Draw): void {
         const screenState = (board() as DalBoard).screenState;
 
-        if (!isValidIcon(buf))
+        if (!screen.isValidImage(buf))
             return;
 
         if (mode & (Draw.Double | Draw.Quad)) {
-            buf = doubleIcon(buf);
+            buf = doubled(buf);
             if (mode & Draw.Quad) {
                 let pbuf = buf;
-                buf = doubleIcon(buf);
+                buf = doubled(buf);
                 decr(pbuf);
             }
         }
 
         let pixwidth = buf.data[1];
         let ptr = 2;
-        const bytewidth = PIX2BYTES(pixwidth);
+        const bytewidth = screen.PIX2BYTES(pixwidth);
         pixwidth = Math.min(pixwidth, visuals.SCREEN_WIDTH);
         while (ptr + bytewidth <= buf.data.length) {
             if (mode & (Draw.Clear | Draw.Xor | Draw.Transparent)) {
@@ -132,24 +268,19 @@ namespace pxsim.screen {
             ptr += bytewidth;
         }
 
-        if (mode & Draw.Double)
+        if (mode & (Draw.Double | Draw.Quad))
             decr(buf);
     }
 
-    export function clear(): void {
+    export function doubled(buf: RefBuffer): RefBuffer {
-        const screenState = (board() as DalBoard).screenState;
+        if (!screen.isValidImage(buf))
-        screenState.clear()
-    }
-
-    export function doubleIcon(buf: RefBuffer): RefBuffer {
-        if (!isValidIcon(buf))
             return null;
         const w = buf.data[1];
         if (w > 126)
             return null;
-        const bw = PIX2BYTES(w);
+        const bw = screen.PIX2BYTES(w);
         const h = ((buf.data.length - 2) / bw) | 0;
-        const bw2 = PIX2BYTES(w * 2);
+        const bw2 = screen.PIX2BYTES(w * 2);
         const out = pins.createBuffer(2 + bw2 * h * 2)
         out.data[0] = 0xf0;
         out.data[1] = w * 2;
@@ -169,7 +300,5 @@ namespace pxsim.screen {
         return out;
     }
 
-    export function dump() {
+
-        // do we need it?
-    }
 }