add slcan serial support

2026-05-23 08:56:19 +08:00
parent b50cb503a8
commit 1cd3badb2d
3 changed files with 253 additions and 24 deletions
--- a/src/slcan.js
+++ b/src/slcan.js
@@ -0,0 +1,132 @@
+class SlcanCodec {
+    constructor() {
+        this.buffer = '';
+        this.decoder = new TextDecoder('ascii');
+    }
+
+    feed(chunk, onFrame, onError) {
+        const text = this.decoder.decode(chunk, { stream: true });
+        if (text.includes('\x07')) {
+            console.warn('SLCAN adapter returned NACK');
+        }
+        this.buffer += text.replace(/\x07/g, '');
+        this.parseBuffer(onFrame);
+    }
+
+    parseBuffer(onFrame) {
+        while (this.buffer.length > 0) {
+            this.buffer = this.buffer.replace(/^[\r\n]+/, '');
+            if (!this.buffer) return;
+
+            const frameStart = this.buffer.search(/[TtRr]/);
+            if (frameStart === -1) {
+                this.buffer = '';
+                return;
+            }
+            if (frameStart > 0) {
+                this.buffer = this.buffer.slice(frameStart);
+            }
+
+            const type = this.buffer[0];
+            if (type === 'T') {
+                if (this.buffer.length < 10) return;
+                const dlcText = this.buffer[9];
+                if (!/^[0-8]$/.test(dlcText)) {
+                    console.warn(`Malformed SLCAN frame header: ${this.buffer.slice(0, 10)}`);
+                    this.buffer = this.buffer.slice(1);
+                    continue;
+                }
+
+                const dlc = parseInt(dlcText, 16);
+                const frameLength = 10 + dlc * 2;
+                if (this.buffer.length < frameLength) return;
+
+                const line = this.buffer.slice(0, frameLength);
+                this.buffer = this.buffer.slice(frameLength).replace(/^[\r\n]+/, '');
+                this.parseLine(line, onFrame);
+                continue;
+            }
+
+            if (type === 't') {
+                if (this.buffer.length < 5) return;
+                const dlcText = this.buffer[4];
+                if (!/^[0-8]$/.test(dlcText)) {
+                    this.buffer = this.buffer.slice(1);
+                    continue;
+                }
+                const frameLength = 5 + parseInt(dlcText, 16) * 2;
+                if (this.buffer.length < frameLength) return;
+                this.buffer = this.buffer.slice(frameLength).replace(/^[\r\n]+/, '');
+                continue;
+            }
+
+            const lineEndIndex = this.findLineEnd();
+            if (lineEndIndex === -1) return;
+            this.buffer = this.buffer.slice(lineEndIndex + 1);
+        }
+    }
+
+    findLineEnd() {
+        const crIndex = this.buffer.indexOf('\r');
+        const lfIndex = this.buffer.indexOf('\n');
+
+        if (crIndex === -1) return lfIndex;
+        if (lfIndex === -1) return crIndex;
+        return Math.min(crIndex, lfIndex);
+    }
+
+    parseLine(line, onFrame) {
+        if (!line) return;
+
+        const type = line[0];
+        if (type === 't' || type === 'r' || type === 'R') return;
+        if (type !== 'T') return;
+
+        if (line.length < 10) {
+            console.warn(`Malformed SLCAN frame: ${line}`);
+            return;
+        }
+
+        const idText = line.slice(1, 9);
+        const dlcText = line[9];
+        if (!/^[0-9a-fA-F]{8}$/.test(idText) || !/^[0-8]$/.test(dlcText)) {
+            console.warn(`Malformed SLCAN frame: ${line}`);
+            return;
+        }
+
+        const dlc = parseInt(dlcText, 16);
+        const dataText = line.slice(10, 10 + dlc * 2);
+        if (dataText.length !== dlc * 2 || !/^[0-9a-fA-F]*$/.test(dataText)) {
+            console.warn(`Malformed SLCAN payload: ${line}`);
+            return;
+        }
+
+        const data = new Uint8Array(dlc);
+        for (let i = 0; i < dlc; i++) {
+            data[i] = parseInt(dataText.slice(i * 2, i * 2 + 2), 16);
+        }
+
+        onFrame?.({
+            id: parseInt(idText, 16) & 0x1FFFFFFF,
+            data,
+            len: dlc,
+        });
+    }
+
+    encodeExtendedFrame(messageId, data, len) {
+        const canId = messageId & 0x1FFFFFFF;
+        const frameLength = Math.min(len, data.length ?? len);
+        if (frameLength > 8) {
+            throw new Error('SLCAN classic CAN frames support a maximum DLC of 8');
+        }
+
+        let dataHex = '';
+        for (let i = 0; i < frameLength; i++) {
+            dataHex += data[i].toString(16).toUpperCase().padStart(2, '0');
+        }
+
+        return `T${canId.toString(16).toUpperCase().padStart(8, '0')}${frameLength.toString(16).toUpperCase()}${dataHex}\r`;
+    }
+}
+
+export default SlcanCodec;