Skip any bytes before the first SLIP_END byte

Author: FozzTexx

lib/bus/rs232/FujiBusPacket.cpp

@@ -1,8 +1,5 @@
 #include "FujiBusPacket.h"
 
-#include "../../include/debug.h"
-#include "utils.h"
-
 typedef struct {
     uint8_t device;   /* Destination Device */
     uint8_t command;  /* Command */
@@ -19,8 +16,7 @@ typedef struct {
 static uint8_t fieldSizeTable[] = {0, 1, 1, 1, 1, 2, 2, 4};
 static uint8_t numFieldsTable[] = {0, 1, 2, 3, 4, 1, 2, 1};
 
-
-std::string FujiBusPacket::decodeSLIP(const std::string &input)
+std::string FujiBusPacket::decodeSLIP(std::string_view input)
 {
     unsigned int idx;
     uint8_t val;
@@ -56,7 +52,7 @@ std::string FujiBusPacket::decodeSLIP(const std::string &input)
     return output;
 }
 
-std::string FujiBusPacket::encodeSLIP(const std::string &input)
+std::string FujiBusPacket::encodeSLIP(std::string_view input)
 {
     unsigned int idx;
     uint8_t val;
@@ -83,36 +79,36 @@ std::string FujiBusPacket::encodeSLIP(const std::string &input)
     return output;
 }
 
-uint8_t FujiBusPacket::calcChecksum(const std::string &input)
+uint8_t FujiBusPacket::calcChecksum(const std::string &buf)
 {
     uint16_t idx, chk;
-    uint8_t *buf = (uint8_t *) input.data();
+    uint8_t *ptr = (uint8_t *) buf.data();
 
-    for (idx = chk = 0; idx < input.size(); idx++)
-        chk = ((chk + buf[idx]) >> 8) + ((chk + buf[idx]) & 0xFF);
+    for (idx = chk = 0; idx < buf.size(); idx++)
+        chk = ((chk + ptr[idx]) >> 8) + ((chk + ptr[idx]) & 0xFF);
     return (uint8_t) chk;
 }
 
-bool FujiBusPacket::parse(const std::string &input)
+bool FujiBusPacket::parse(std::string_view input)
 {
     std::string decoded;
     fujibus_header *hdr;
+    std::string_view slipEncoded = input;
 
-    Debug_printv("Incoming:\n%s\n", util_hexdump(input.data(), input.size()).c_str());
+    size_t slipMarker = input.find(SLIP_END);
+    if (slipMarker != std::string::npos)
+        slipEncoded = std::string_view(input).substr(slipMarker);
 
-    if (input.size() < sizeof(fujibus_header) + 2)
+    if (slipEncoded.size() < sizeof(fujibus_header) + 2)
         return false;
-    if (((uint8_t) input[0]) != SLIP_END || ((uint8_t) input.back()) != SLIP_END)
+    if (((uint8_t) slipEncoded[0]) != SLIP_END || ((uint8_t) slipEncoded.back()) != SLIP_END)
         return false;
 
-    decoded = decodeSLIP(input);
-    Debug_printv("Decoded:\n%s\n", util_hexdump(decoded.data(), decoded.size()).c_str());
+    decoded = decodeSLIP(slipEncoded);
 
     if (decoded.size() < sizeof(fujibus_header))
         return false;
     hdr = (fujibus_header *) &decoded[0];
-    Debug_printv("Header: dev:%02x cmd:%02x len:%d chk:%02x fld:%02x",
-                 hdr->device, hdr->command, hdr->length, hdr->checksum, hdr->descr);
 
     if (hdr->length != decoded.size())
         return false;
@@ -231,12 +227,11 @@ std::string FujiBusPacket::serialize()
     hptr = (fujibus_header *) output.data();
     *hptr = hdr;
     hptr->checksum = calcChecksum(output);
-    Debug_printv("Packet header: dev:%02x cmd:%02x len:%d chk:%02x fld:%02x",
-                 hptr->device, hptr->command, hptr->length, hptr->checksum, hptr->descr);
-    return encodeSLIP(output);
+    auto encoded = encodeSLIP(output);
+    return encoded;
 }
 
-std::unique_ptr<FujiBusPacket> FujiBusPacket::fromSerialized(const std::string &input)
+std::unique_ptr<FujiBusPacket> FujiBusPacket::fromSerialized(std::string_view input)
 {
     auto packet = std::make_unique<FujiBusPacket>();
     if (!packet->parse(input))

lib/bus/rs232/FujiBusPacket.h

@@ -8,6 +8,7 @@
 #include <optional>
 #include <string>
 #include <memory>
+#include <cassert>
 
 enum {
     SLIP_END     = 0xC0,
@@ -28,8 +29,7 @@ struct PacketParam {
                       "Param can only be uint8_t, uint16_t, or uint32_t");
     }
     PacketParam(uint32_t v, uint8_t s) : value(v), size(s) {
-        if (s != 1 && s != 2 && s != 4)
-            throw std::invalid_argument("Param size must be 1, 2, or 4");
+        assert(s == 1 || s == 2 || s == 4);
     }
 };
 
@@ -41,9 +41,9 @@ class FujiBusPacket
     std::vector<PacketParam> _params;
     std::optional<std::string> _data = std::nullopt;
 
-    std::string decodeSLIP(const std::string &input);
-    std::string encodeSLIP(const std::string &input);
-    bool parse(const std::string &input);
+    std::string decodeSLIP(std::string_view input);
+    std::string encodeSLIP(std::string_view input);
+    bool parse(std::string_view input);
     uint8_t calcChecksum(const std::string &buf);
 
     void processArg(uint8_t v)  { _params.emplace_back(v); }
@@ -62,7 +62,7 @@ class FujiBusPacket
         (processArg(std::forward<Args>(args)), ...);  // fold expression
     }
 
-    static std::unique_ptr<FujiBusPacket> fromSerialized(const std::string &input);
+    static std::unique_ptr<FujiBusPacket> fromSerialized(std::string_view input);
 
     std::string serialize();