///////////////////////////////////////////////////////////////////////
// boot.c
//
// Written: Jacob Pease jacob.pease@okstate.edu 7/22/2024
//
// Purpose: Main bootloader entry point
//
// 
//
// A component of the Wally configurable RISC-V project.
// 
// Copyright (C) 2021-23 Harvey Mudd College & Oklahoma State University
//
// SPDX-License-Identifier: Apache-2.0 WITH SHL-2.1
//
// Licensed under the Solderpad Hardware License v 2.1 (the
// “License”); you may not use this file except in compliance with the
// License, or, at your option, the Apache License version 2.0. You
// may obtain a copy of the License at
//
// https://solderpad.org/licenses/SHL-2.1/
//
// Unless required by applicable law or agreed to in writing, any work
// distributed under the License is distributed on an “AS IS” BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
// implied. See the License for the specific language governing
// permissions and limitations under the License.
///////////////////////////////////////////////////////////////////////

#include <stddef.h>
#include "boot.h"
#include "gpt.h"
#include "uart.h"
#include "spi.h"
#include "sd.h"
#include "time.h"
#include "riscv.h"
#include "fail.h"


// Maximum SD card clock frequency is either 20MHz or half of the
// system clock

/*
PSEUDOCODE:
transmit 8 dummy bytes
wait for receive fifo to get a byte.
- as soon as a byte is in the receive fifo
- process the byte and increment a byte counter.
when 8 bytes are transferred


 */

// crc16 table to reduce byte processing time
static const uint16_t crctable[256] = {
  0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7, 
  0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef, 
  0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6, 
  0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de, 
  0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485, 
  0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d, 
  0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4, 
  0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc, 
  0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823, 
  0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b, 
  0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12, 
  0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a, 
  0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41, 
  0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49, 
  0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70, 
  0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78, 
  0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f, 
  0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067, 
  0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e, 
  0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256, 
  0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d, 
  0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405, 
  0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c, 
  0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634, 
  0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab, 
  0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3, 
  0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a, 
  0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92, 
  0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9, 
  0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1, 
  0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8, 
  0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0 
};

int disk_read(BYTE * buf, LBA_t sector, UINT count) {
  uint64_t r;
  UINT i, j;
  volatile uint8_t *p = buf;

  // Quarter of the Systemclock, divided by the number of bits in a block
  // equals the number of blocks per second transferred.
  UINT modulus = SDCCLOCK/(8*512);

  uint8_t crc = 0;
  crc = crc7(crc, 0x40 | SD_CMD_READ_BLOCK_MULTIPLE);
  crc = crc7(crc, (sector >> 24) & 0xff);
  crc = crc7(crc, (sector >> 16) & 0xff);
  crc = crc7(crc, (sector >> 8) & 0xff);
  crc = crc7(crc, sector & 0xff);
  crc = crc | 1;
  
  if ((r = sd_cmd(18, sector & 0xffffffff, crc) & 0xff) != 0x00) {
    print_uart("disk_read: CMD18 failed. r = 0x");
    print_uart_byte(r);
    print_uart("\r\n");
    fail();
    // return -1;
  }

  print_uart("\r          Blocks loaded: ");
  print_uart("0");
  print_uart("/");
  print_uart_dec(count);
  // write_reg(SPI_CSMODE, SIFIVE_SPI_CSMODE_MODE_HOLD);
  // Begin reading blocks
  for (i = 0; i < count; i++) {
    uint16_t crc, crc_exp;
    uint64_t n = 0;
    uint64_t readCount = 0;

    // Wait for data token
    while((r = spi_dummy()) != SD_DATA_TOKEN);

    crc = 0;
    /* n = 512; */
    /* do { */
    /*   uint8_t x = spi_dummy(); */
    /*   *p++ = x; */
    /*   crc = crc16(crc, x); */
    /* } while (--n > 0); */

    n = 512/8;
    do {
      // Send 8 dummy bytes (fifo should be empty)
      for (j = 0; j < 8; j++) {
        spi_sendbyte(0xff);
      }

      // Reset counter. Process bytes AS THEY COME IN.
      for (j = 0; j < 8; j++) {
        while (!(read_reg(SPI_IP) & 2)) {}
        uint8_t x = spi_readbyte();
        *p++ = x;
        // crc = crc16(crc, x);
        crc = ((crc << 8) ^ crctable[x ^ (crc >> 8)]) & 0xffff;
      }
    } while(--n > 0);

    /* n = 512; */
    /* // Initially fill the transmit fifo */
    /* for (j = 0; j < 8; j++) { */
    /*   spi_sendbyte(0xff); */
    /* } */

    
    /* while (n > 0) { */
    /*   // Wait for bytes to be received */
    /*   while (!(read_reg(SPI_IP) & 2)) {} */
    /*   // Read byte */
    /*   uint8_t x = spi_readbyte(); */
    /*   // Send another dummy byte */
    /*   if (n > 8) { */
    /*     spi_sendbyte(0xff); */
    /*   } */
    /*   // Place received byte into memory */
    /*   *p++ = x; */
    /*   // Update CRC16 with fast table based method */
    /*   crc = ((crc << 8) ^ crctable[x ^ (crc >> 8)]) & 0xffff; */
    /*   n = n - 1; */
    /* } */
    
    // Read CRC16 and check
    crc_exp = ((uint16_t)spi_dummy() << 8);
    crc_exp |= spi_dummy();

    if (crc != crc_exp) {
      print_uart("Stinking CRC16 didn't match on block read.\r\n");
      print_uart_int(i);
      print_uart("\r\n");
      //return -1;
      fail();
    }

    if ( (i % modulus) == 0 ) {
      print_uart("\r          Blocks loaded: ");
      print_uart_dec(i);
      print_uart("/");
      print_uart_dec(count);
    }

  }

  sd_cmd(SD_CMD_STOP_TRANSMISSION, 0, 0x01);

  print_uart("\r          Blocks loaded: ");
  print_uart_dec(count);
  print_uart("/");
  print_uart_dec(count);
  print_uart("\r\n");
  return 0;
}

// copyFlash: --------------------------------------------------------
// A lot happens in this function:
// * The Wally banner is printed
// * The peripherals are initialized
void copyFlash(QWORD address, QWORD * Dst, DWORD numBlocks) {
  int ret = 0;

  // Initialize UART for messages
  init_uart(SYSTEMCLOCK, 115200);
  
  // Print the wally banner
  print_uart(BANNER);

  /* print_uart("System clock speed: "); */
  /* print_uart_dec(SYSTEMCLOCK); */
  /* print_uart("\r\n"); */

  // Intialize the SD card
  init_sd(SYSTEMCLOCK, SDCCLOCK);
  
  ret = gpt_load_partitions();
}