From 72ab55255478a8c87f670e12d9e4475279759137 Mon Sep 17 00:00:00 2001 From: Pierre Gondois Date: Thu, 30 Sep 2021 08:48:16 +0100 Subject: [PATCH] DynamicTablesPkg: Add AmlGetEisaIdFromString() to AcpiHelperLib Add a function converting a 7 characters string to its UINT32 EISAID. The algorithm used to create the EISAID is described in the ACPI 6.4 specification, s19.3.4 "ASL Macros". Reviewed-by: Sami Mujawar Signed-off-by: Pierre Gondois --- .../Include/Library/AcpiHelperLib.h | 17 +++++ .../Library/Common/AcpiHelperLib/AcpiHelper.c | 69 +++++++++++++++++++ 2 files changed, 86 insertions(+) diff --git a/DynamicTablesPkg/Include/Library/AcpiHelperLib.h b/DynamicTablesPkg/Include/Library/AcpiHelperLib.h index 094392a1a6..a93e95e919 100644 --- a/DynamicTablesPkg/Include/Library/AcpiHelperLib.h +++ b/DynamicTablesPkg/Include/Library/AcpiHelperLib.h @@ -73,4 +73,21 @@ IsValidAcpiId ( IN CONST CHAR8 * Hid ); +/** Convert a EisaId string to its compressed UINT32 equivalent. + + Cf. ACPI 6.4 specification, s19.3.4 "ASL Macros": "Eisaid" + + @param [in] EisaIdStr Input EisaId string. + @param [out] EisaIdInt Output EisaId UINT32 (compressed). + + @retval EFI_SUCCESS The function completed successfully. + @retval EFI_INVALID_PARAMETER Invalid parameter. +**/ +EFI_STATUS +EFIAPI +AmlGetEisaIdFromString ( + IN CONST CHAR8 * EisaIdStr, + OUT UINT32 * EisaIdInt + ); + #endif // ACPI_HELPER_LIB_H_ diff --git a/DynamicTablesPkg/Library/Common/AcpiHelperLib/AcpiHelper.c b/DynamicTablesPkg/Library/Common/AcpiHelperLib/AcpiHelper.c index 0b566f0502..5afd257e49 100644 --- a/DynamicTablesPkg/Library/Common/AcpiHelperLib/AcpiHelper.c +++ b/DynamicTablesPkg/Library/Common/AcpiHelperLib/AcpiHelper.c @@ -139,3 +139,72 @@ IsValidAcpiId ( return TRUE; } + +/** Convert a EisaId string to its compressed UINT32 equivalent. + + Cf. ACPI 6.4 specification, s19.3.4 "ASL Macros": "Eisaid" + + @param [in] EisaIdStr Input EisaId string. + @param [out] EisaIdInt Output EisaId UINT32 (compressed). + + @retval EFI_SUCCESS The function completed successfully. + @retval EFI_INVALID_PARAMETER Invalid parameter. +**/ +EFI_STATUS +EFIAPI +AmlGetEisaIdFromString ( + IN CONST CHAR8 * EisaIdStr, + OUT UINT32 * EisaIdInt + ) +{ + if ((EisaIdStr == NULL) || + (!IsValidPnpId (EisaIdStr)) || + (EisaIdInt == NULL)) { + ASSERT (0); + return EFI_INVALID_PARAMETER; + } + + /* Cf. ACPI 6.4 specification, s19.3.4 "ASL Macros": "Eisaid" + + Converts and compresses the 7-character text argument into its corresponding + 4-byte numeric EISA ID encoding (Integer). This can be used when declaring + IDs for devices that are EISA IDs. + + The algorithm used to convert the TextID is as shown in the following + example: + Starting with a seven character input string "PNP0303", we want to create + a DWordConst. This string contains a three character manufacturer code + "PNP", a three character hex product identifier "030", and a one character + revision identifier "3". + The compressed manufacturer code is created as follows: + 1) Find hex ASCII value for each letter + 2) Subtract 40h from each ASCII value + 3) Retain 5 least significant bits for each letter and discard remaining + 0's: + + Byte 0: + Bit 7: reserved (0) + Bit 6-2: 1st character of compressed mfg code "P" + Bit 1-0: Upper 2 bits of 2nd character of mfg code "N" + Byte 1: + Bit 7-5: Lower 3 bits of 2nd character of mfg code "N" + Bit 4-0: 3rd character of mfg code "P" + Byte 2: + Bit 7-4: 1st hex digit of product number "0" + Bit 3-0: 2nd hex digit of product number "3" + Byte 3: + Bit 7-4: 3rd hex digit of product number "0" + Bit 3-0: 4th hex digit of product number "3" + */ + *EisaIdInt = SwapBytes32 ( + ((EisaIdStr[0] - 0x40) << 26) | + ((EisaIdStr[1] - 0x40) << 21) | + ((EisaIdStr[2] - 0x40) << 16) | + (HexFromAscii (EisaIdStr[3]) << 12) | + (HexFromAscii (EisaIdStr[4]) << 8) | + (HexFromAscii (EisaIdStr[5]) << 4) | + (HexFromAscii (EisaIdStr[6])) + ); + + return EFI_SUCCESS; +} -- 2.39.2