diff options
| -rw-r--r-- | src/TII.cpp | 38 | ||||
| -rw-r--r-- | src/TII.h | 23 |
2 files changed, 38 insertions, 23 deletions
diff --git a/src/TII.cpp b/src/TII.cpp index 8ec4c35..09a4920 100644 --- a/src/TII.cpp +++ b/src/TII.cpp @@ -153,8 +153,8 @@ TII::TII(unsigned int dabmode, const tii_config_t& tii_config) : throw TIIError("TII::TII comb not valid!"); } - m_enabled_carriers.clear(); - m_enabled_carriers.resize(m_carriers); + m_Acp.clear(); + m_Acp.resize(m_carriers); prepare_pattern(); } @@ -199,11 +199,27 @@ int TII::process(Buffer* dataIn, Buffer* dataOut) * This is because we only enable 32 out of 1536 carriers, not because * every carrier is lower power. */ - for (size_t i = 0; i < m_enabled_carriers.size(); i++) { - // See header file for an explanation of the old variant - if (m_enabled_carriers[i]) { - out[i] = (m_conf.old_variant ? in[i+1] : in[i]); - out[i+1] = in[i+1]; + for (size_t i = 0; i < m_Acp.size(); i++) { + /* See header file for an explanation of the old variant. + * + * A_{c,p}(k) and A_{c,p}(k-1) are never both simultaneously true, + * so instead of doing the sum inside z_{m,0,k}, we could do + * + * if (m_Acp[i]) out[i] = in[i]; + * if (m_Acp[i-1]) out[i] = in[i-1] + * + * (Considering only the new variant) + * + * To avoid messing with indices, we substitute j = i-1 + * + * if (m_Acp[i]) out[i] = in[i]; + * if (m_Acp[j]) out[j+1] = in[j] + * + * and fuse the two conditionals together: + */ + if (m_Acp[i]) { + out[i] = in[i]; + out[i+1] = (m_conf.old_variant ? in[i+1] : in[i]); } } } @@ -217,11 +233,11 @@ int TII::process(Buffer* dataIn, Buffer* dataOut) void TII::enable_carrier(int k) { int ix = m_carriers/2 + k; - if (ix < 0 or ix+1 >= (ssize_t)m_enabled_carriers.size()) { + if (ix < 0 or ix+1 >= (ssize_t)m_Acp.size()) { throw TIIError("TII::enable_carrier invalid k!"); } - m_enabled_carriers[ix] = true; + m_Acp[ix] = true; } void TII::prepare_pattern() { @@ -230,8 +246,8 @@ void TII::prepare_pattern() { std::lock_guard<std::mutex> lock(m_enabled_carriers_mutex); // Clear previous pattern - for (size_t i = 0; i < m_enabled_carriers.size(); i++) { - m_enabled_carriers[i] = false; + for (size_t i = 0; i < m_Acp.size(); i++) { + m_Acp[i] = false; } // This could be written more efficiently, but since it is @@ -43,11 +43,9 @@ struct tii_config_t { - tii_config_t() : enable(false), comb(0), pattern(0), old_variant(false) {} - - bool enable; - int comb; - int pattern; + bool enable = false; + int comb = 0; + int pattern = 0; /* EN 300 401 clause 14.8 describes how to generate the TII signal, and * defines z_{m,0,k}: @@ -69,7 +67,7 @@ struct tii_config_t * The option 'old_variant' allows the user to choose between this * old incorrect implementation and the new conforming one. */ - bool old_variant; + bool old_variant = false; }; class TIIError : public std::runtime_error { @@ -96,11 +94,11 @@ class TII : public ModCodec, public RemoteControllable const std::string& parameter) const; protected: - // Fill m_enabled_carriers with the correct carriers for the pattern/comb + // Fill m_Acp with the correct carriers for the pattern/comb // combination void prepare_pattern(void); - // prerequisites: calling thread must hold m_enabled_carriers mutex + // prerequisites: calling thread must hold m_Acp mutex void enable_carrier(int k); // Configuration settings @@ -116,12 +114,13 @@ class TII : public ModCodec, public RemoteControllable std::string m_name; - // m_enabled_carriers is read by modulator thread, and written + // m_Acp is read by modulator thread, and written // to by RC thread. mutable std::mutex m_enabled_carriers_mutex; - // m_enabled_carriers is true only for the first carrier in the - // active pair - std::vector<bool> m_enabled_carriers; + // m_Acp corresponds to the A_{c,p}(k) function from the spec, except + // that the leftmost carrier is at index 0, and not at -m_carriers/2 like + // in the spec. + std::vector<bool> m_Acp; }; |