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Adding Long Packet

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This commit is contained in:
Lee Lup Yuen 2022-10-06 11:58:31 +08:00
parent 5e33e3d476
commit e2f6aa6dd7
1 changed files with 34 additions and 28 deletions
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62
display.zig
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@ -90,43 +90,49 @@ fn compose_long_packet(
) []u8 {
_ = buf;
debug("compose_long_packet: channel={}, cmd={x}, len={}", .{ channel, cmd, len });
// Packet Header (4 bytes):
// TODO:
// - Data Identifier (DI) (1 byte):
// Virtual Channel Identifier (Bits 6 to 7)
// Data Type (Bits 0 to 5)
// (Virtual Channel should be 0, I think)
const dc = 0;
// Data Identifier (DI) (1 byte):
// Virtual Channel Identifier (Bits 6 to 7)
// Data Type (Bits 0 to 5)
// (Virtual Channel should be 0, I think)
assert(cmd < (1 << 6));
const vc: u8 = 0;
const dt: u8 = cmd;
const di: u8 = (vc << 6) | dt;
// - Word Count (WC) (2 bytes)：
// Number of bytes in the Packet Payload
const wc = @intCast(u16, len);
const wcl = @intCast(u8, wc & 0xff);
const wch = @intCast(u8, wc >> 8);
// Word Count (WC) (2 bytes)：
// Number of bytes in the Packet Payload
const wc: u16 = @intCast(u16, len);
const wcl: u8 = @intCast(u8, wc & 0xff);
const wch: u8 = @intCast(u8, wc >> 8);
// TODO:
// - Error Correction Code (ECC) (1 byte):
// Allow single-bit errors to be corrected and 2-bit errors to be detected in the Packet Header
// See "12.3.6.12: Error Correction Code", Page 208:
// https://github.com/sipeed/sipeed2022_autumn_competition/blob/main/assets/BL808_RM_en.pdf)
const ecc = 0;
const header = [4]u8 { dc, wcl, wch, ecc };
// TODO: Error Correction Code (ECC) (1 byte):
// Allow single-bit errors to be corrected and 2-bit errors to be detected in the Packet Header
// See "12.3.6.12: Error Correction Code", Page 208:
// https://github.com/sipeed/sipeed2022_autumn_competition/blob/main/assets/BL808_RM_en.pdf)
const ecc: u8 = 0;
// TODO: Checksum (CS) (2 bytes):
// 16-bit Cyclic Redundancy Check (CRC)
// See "12.3.6.13: Packet Footer", Page 210:
// https://github.com/sipeed/sipeed2022_autumn_competition/blob/main/assets/BL808_RM_en.pdf)
const cs: u16 = 0;
const csl: u8 = @intCast(u8, cs & 0xff);
const csh: u8 = @intCast(u8, cs >> 8);
// Packet Header (4 bytes): Data Identifier, Word Count, Error Correction COde
const header = [4]u8 { di, wcl, wch, ecc };
_ = header;
// Packet Payload:
// - Data (0 to 65,541 bytes):
// Number of data bytes should match the Word Count (WC)
// Data (0 to 65,541 bytes):
// Number of data bytes should match the Word Count (WC)
assert(len <= 65_541);
// TODO: Packet Footer:
// - Checksum (CS) (2 bytes):
// 16-bit Cyclic Redundancy Check (CRC)
// See "12.3.6.13: Packet Footer", Page 210:
// https://github.com/sipeed/sipeed2022_autumn_competition/blob/main/assets/BL808_RM_en.pdf)
const footer = [2]u8 { 0, 0 };
// Packet Footer: Checksum
const footer = [2]u8 { csl, csh };
_ = footer;
// TODO: Concatenate the header, payload and footer
// TODO: Packet = Packet Header + Payload + Packet Footer
var pkt = std.mem.zeroes([1024]u8);
assert(pkt.len >= header.len + len + footer.len); // Increase pkt size
std.mem.copy(u8, pkt[0..header.len], &header);