X-Git-Url: https://git.gag.com/?p=fw%2Faltos;a=blobdiff_plain;f=src%2Fcore%2Fao_fec_rx.c;h=0d400bb0b882ae90dd69c46eb58e9412e7347579;hp=69e9c1f5b7da393f9757e9b88b6448a1cf95b31d;hb=f1ae622eff60e05c1f5d8f822a3cf6a85750c6cc;hpb=936ecad62596f34773afb7460b10f63df7d0896d diff --git a/src/core/ao_fec_rx.c b/src/core/ao_fec_rx.c index 69e9c1f5..0d400bb0 100644 --- a/src/core/ao_fec_rx.c +++ b/src/core/ao_fec_rx.c @@ -18,6 +18,16 @@ #include #include +#ifdef MEGAMETRUM +#include +#endif + +#if AO_PROFILE +#include + +uint32_t ao_fec_decode_start, ao_fec_decode_end; +#endif + /* * byte order repeats through 3 2 1 0 * @@ -40,34 +50,35 @@ * 18/19 10/11 08/09 00/01 */ +static const uint8_t ao_interleave_order[] = { + 0x1e, 0x16, 0x0e, 0x06, + 0x1c, 0x14, 0x0c, 0x04, + 0x1a, 0x12, 0x0a, 0x02, + 0x18, 0x10, 0x08, 0x00 +}; + static inline uint16_t ao_interleave_index(uint16_t i) { - uint8_t l = i & 0x1e; - uint16_t h = i & ~0x1e; - uint8_t o = 0x1e ^ (((l >> 2) & 0x6) | ((l << 2) & 0x18)); - return h | o; + return (i & ~0x1e) | ao_interleave_order[(i & 0x1e) >> 1]; } -struct ao_soft_sym { - uint8_t a, b; -}; - #define NUM_STATE 8 #define NUM_HIST 8 -#define MOD_HIST(b) ((b) & 7) - -#define V_0 0xc0 -#define V_1 0x40 - -static const struct ao_soft_sym ao_fec_decode_table[NUM_STATE][2] = { -/* next 0 1 state */ - { { V_0, V_0 }, { V_1, V_1 } } , /* 000 */ - { { V_0, V_1 }, { V_1, V_0 } }, /* 001 */ - { { V_1, V_1 }, { V_0, V_0 } }, /* 010 */ - { { V_1, V_0 }, { V_0, V_1 } }, /* 011 */ - { { V_1, V_1 }, { V_0, V_0 } }, /* 100 */ - { { V_1, V_0 }, { V_0, V_1 } }, /* 101 */ - { { V_0, V_0 }, { V_1, V_1 } }, /* 110 */ - { { V_0, V_1 }, { V_1, V_0 } } /* 111 */ + +#define V_0 0xff +#define V_1 0x00 + +/* + * These are just the 'zero' states; the 'one' states mirror them + */ +static const uint8_t ao_fec_decode_table[NUM_STATE*2] = { + V_0, V_0, /* 000 */ + V_0, V_1, /* 001 */ + V_1, V_1, /* 010 */ + V_1, V_0, /* 011 */ + V_1, V_1, /* 100 */ + V_1, V_0, /* 101 */ + V_0, V_0, /* 110 */ + V_0, V_1 /* 111 */ }; static inline uint8_t @@ -76,14 +87,6 @@ ao_next_state(uint8_t state, uint8_t bit) return ((state << 1) | bit) & 0x7; } -static inline uint16_t ao_abs(int16_t x) { return x < 0 ? -x : x; } - -static inline uint16_t -ao_cost(struct ao_soft_sym a, struct ao_soft_sym b) -{ - return ao_abs(a.a - b.a) + ao_abs(a.b - b.b); -} - /* * 'in' is 8-bits per symbol soft decision data * 'len' is input byte length. 'out' must be @@ -91,25 +94,29 @@ ao_cost(struct ao_soft_sym a, struct ao_soft_sym b) */ uint8_t -ao_fec_decode(uint8_t *in, uint16_t len, uint8_t *out, uint8_t out_len, uint16_t (*callback)()) +ao_fec_decode(const uint8_t *in, uint16_t len, uint8_t *out, uint8_t out_len, uint16_t (*callback)()) { - static uint16_t cost[2][NUM_STATE]; /* path cost */ + static uint32_t cost[2][NUM_STATE]; /* path cost */ static uint16_t bits[2][NUM_STATE]; /* save bits to quickly output them */ + uint16_t i; /* input byte index */ uint16_t b; /* encoded symbol index (bytes/2) */ uint16_t o; /* output bit index */ uint8_t p; /* previous cost/bits index */ uint8_t n; /* next cost/bits index */ uint8_t state; /* state index */ - uint8_t bit; /* original encoded bit index */ const uint8_t *whiten = ao_fec_whiten_table; uint16_t interleave; /* input byte array index */ - struct ao_soft_sym s; /* input symbol pair */ + uint8_t s0, s1; uint16_t avail; + uint16_t crc = AO_FEC_CRC_INIT; +#if AO_PROFILE + uint32_t start_tick; +#endif p = 0; for (state = 0; state < NUM_STATE; state++) { - cost[0][state] = 0xffff; + cost[0][state] = 0x7fffffff; bits[0][state] = 0; } cost[0][0] = 0; @@ -119,6 +126,14 @@ ao_fec_decode(uint8_t *in, uint16_t len, uint8_t *out, uint8_t out_len, uint16_t else avail = len; +#if AO_PROFILE + if (!avail) { + avail = callback(); + if (!avail) + return 0; + } + start_tick = ao_profile_tick(); +#endif o = 0; for (i = 0; i < len; i += 2) { b = i/2; @@ -127,44 +142,52 @@ ao_fec_decode(uint8_t *in, uint16_t len, uint8_t *out, uint8_t out_len, uint16_t if (!avail) { avail = callback(); if (!avail) - break; + return 0; } /* Fetch one pair of input bytes, de-interleaving * the input. */ interleave = ao_interleave_index(i); - s.a = in[interleave]; - s.b = in[interleave+1]; + s0 = in[interleave]; + s1 = in[interleave+1]; + + avail -= 2; /* Reset next costs to 'impossibly high' values so that * the first path through this state is cheaper than this */ for (state = 0; state < NUM_STATE; state++) - cost[n][state] = 0xffff; + cost[n][state] = 0x7fffffff; /* Compute path costs and accumulate output bit path * for each state and encoded bit value */ for (state = 0; state < NUM_STATE; state++) { - for (bit = 0; bit < 2; bit++) { - int bit_cost = cost[p][state] + ao_cost(s, ao_fec_decode_table[state][bit]); - uint8_t bit_state = ao_next_state(state, bit); - - /* Only track the minimal cost to reach - * this state; the best path can never - * go through the higher cost paths as - * total path cost is cumulative - */ - if (bit_cost < cost[n][bit_state]) { - cost[n][bit_state] = bit_cost; - bits[n][bit_state] = (bits[p][state] << 1) | (state & 1); + uint32_t bitcost = ((uint32_t) (s0 ^ ao_fec_decode_table[(state<<1)]) + + (uint32_t) (s1 ^ ao_fec_decode_table[(state<<1)+1])); + { + uint32_t cost0 = cost[p][state] + bitcost; + uint8_t state0 = ao_next_state(state, 0); + + if (cost0 < cost[n][state0]) { + cost[n][state0] = cost0; + bits[n][state0] = (bits[p][state] << 1) | (state & 1); + } + } + { + uint32_t cost1 = cost[p][state] + 510 - bitcost; + uint8_t state1 = ao_next_state(state, 1); + + if (cost1 < cost[n][state1]) { + cost[n][state1] = cost1; + bits[n][state1] = (bits[p][state] << 1) | (state & 1); } } } #if 0 - printf ("bit %3d symbol %2x %2x:", i/2, s.a, s.b); + printf ("bit %3d symbol %2x %2x:", i/2, s0, s1); for (state = 0; state < NUM_STATE; state++) { printf (" %5d(%04x)", cost[n][state], bits[n][state]); } @@ -186,7 +209,7 @@ ao_fec_decode(uint8_t *in, uint16_t len, uint8_t *out, uint8_t out_len, uint16_t * it will be seven. */ int8_t dist = b - (o + 8); /* distance to last ready-for-writing bit */ - uint16_t min_cost; /* lowest cost */ + uint32_t min_cost; /* lowest cost */ uint8_t min_state; /* lowest cost state */ /* Find the best fit at the current point @@ -216,11 +239,23 @@ ao_fec_decode(uint8_t *in, uint16_t len, uint8_t *out, uint8_t out_len, uint16_t i/2, min_cost, o + 8, min_state, (bits[p][min_state] >> dist) & 0xff, *whiten); #endif if (out_len) { - *out++ = (bits[p][min_state] >> dist) ^ *whiten++; + uint8_t byte = (bits[p][min_state] >> dist) ^ *whiten++; + + if (out_len > 2) { + crc = ao_fec_crc_byte(byte, crc); + *out++ = byte; + } else { + *out++ = byte ^ (crc >> 8); + crc <<= 8; + } --out_len; } o += 8; } } +#if AO_PROFILE + ao_fec_decode_start = start_tick; + ao_fec_decode_end = ao_profile_tick(); +#endif return len/16; }