From e15c49c5a5401cd001aed70030e3c62f5ad7c35a Mon Sep 17 00:00:00 2001 From: Xavier Arteaga Date: Tue, 28 Apr 2020 11:03:51 +0200 Subject: [PATCH] Fix EVM hard-decision performance --- lib/include/srslte/phy/modem/evm.h | 36 ++++++++++++++++++++++++------ 1 file changed, 29 insertions(+), 7 deletions(-) diff --git a/lib/include/srslte/phy/modem/evm.h b/lib/include/srslte/phy/modem/evm.h index da65ffaf5..6c37a7d97 100644 --- a/lib/include/srslte/phy/modem/evm.h +++ b/lib/include/srslte/phy/modem/evm.h @@ -130,13 +130,35 @@ static inline void srslte_evm_buffer_resize(srslte_evm_buffer_t* q, uint32_t nof /** * Template for hard decision taking */ -#define HARD_DECISION(SOFTBITS, HARDBITS, NOF_SOFTBITS) \ +#define HARD_DECISION(LLR_T, SOFTBITS, HARDBITS, NOF_SOFTBITS) \ do { \ - for (uint32_t i = 0, k = 0; k < NOF_SOFTBITS; i++) { \ - uint8_t w = 0; \ - for (int j = 0; j < 8 && k < NOF_SOFTBITS; j++, k++) { \ - w |= (SOFTBITS[k] > 0) ? ((uint32_t)1 << (uint32_t)(7 - j)) : 0; \ - } \ + /* Typecasts pointer type to minimum width */ \ + uint8_t* ptr = (uint8_t*)SOFTBITS; \ + \ + /* Big endian compensation, ptr needs to point at the MSB */ \ + ptr += sizeof(LLR_T) - 1UL; \ + \ + for (uint32_t i = 0; i < NOF_SOFTBITS / 8; i++) { \ + /* Default mask */ \ + uint8_t w = 0xff; \ + \ + /* For each soft bit, take MSB ad collocate in right position */ \ + w ^= (*ptr & 0x80); \ + ptr += sizeof(LLR_T); \ + w ^= (*ptr & 0x80) >> 1; \ + ptr += sizeof(LLR_T); \ + w ^= (*ptr & 0x80) >> 2; \ + ptr += sizeof(LLR_T); \ + w ^= (*ptr & 0x80) >> 3; \ + ptr += sizeof(LLR_T); \ + w ^= (*ptr & 0x80) >> 4; \ + ptr += sizeof(LLR_T); \ + w ^= (*ptr & 0x80) >> 5; \ + ptr += sizeof(LLR_T); \ + w ^= (*ptr & 0x80) >> 6; \ + ptr += sizeof(LLR_T); \ + w ^= (*ptr & 0x80) >> 7; \ + ptr += sizeof(LLR_T); \ HARDBITS[i] = w; \ } \ } while (false) @@ -166,7 +188,7 @@ static inline void srslte_evm_buffer_resize(srslte_evm_buffer_t* q, uint32_t nof uint32_t nsymbols = nof_bits / modem_table->nbits_x_symbol; \ \ /* Hard decision */ \ - HARD_DECISION(llr, q->hard_bits, nof_bits); \ + HARD_DECISION(LLR_T, llr, q->hard_bits, nof_bits); \ \ /* Modulate */ \ srslte_mod_modulate_bytes(modem_table, q->hard_bits, q->symbols, nof_bits); \