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diff --git a/Lessons/Lesson_Checkbox/README.md b/Lessons/Lesson_Checkbox/README.md new file mode 100644 index 0000000..1ac4b3c --- /dev/null +++ b/Lessons/Lesson_Checkbox/README.md @@ -0,0 +1,102 @@ +Now let's try to actually save some user input with a form. + +For the data we will choose the most simple element - checkbox (https://edk2-docs.gitbook.io/edk-ii-vfr-specification/2_vfr_description_in_bnf/211_vfr_form_definition#2.11.6.5.1-vfr-checkbox-statement-definition) + +Crete new application with a form and insert the following code inside: +``` +checkbox + prompt = STRING_TOKEN(CHECKBOX_TITLE), + help = STRING_TOKEN(CHECKBOX_HELP), +endcheckbox; +``` + +This will give you the following element on form + + + +Which you can toggle with a spacebar + + + +The checkbox element will produce `EFI_IFR_CHECKBOX` and `EFI_IFR_END` opcodes: +``` + checkbox +>00000039: 06 8E 05 00 06 00 01 00 00 00 FF FF 00 00 + prompt = STRING_TOKEN(0x0005), + help = STRING_TOKEN(0x0006), + endcheckbox; +>00000047: 29 02 +``` + +Here is a definition for the `EFI_IFR_CHECKBOX`: +``` +EFI_IFR_CHECKBOX + +Summary: +Creates a boolean checkbox. + +Prototype: + +#define EFI_IFR_CHECKBOX_OP 0x06 + +typedef struct _EFI_IFR_CHECKBOX { + EFI_IFR_OP_HEADER Header; + EFI_IFR_QUESTION_HEADER Question; + UINT8 Flags; +} EFI_IFR_CHECKBOX; + +Members: +Header The standard question header, where Header.OpCode = EFI_IFR_CHECKBOX_OP. +Question The standard question header. +Flags Flags that describe the behavior of the question. All undefined bits should be zero. + +Description: +Creates a Boolean checkbox question and adds it to the current form. The checkbox has two values: +FALSE if the box is not checked and TRUE if it is. +``` +And for its field `EFI_IFR_QUESTION_HEADER`: +``` +EFI_IFR_QUESTION_HEADER + +Summary: +Standard question header. + +Prototype: + +typedef struct _EFI_IFR_QUESTION_HEADER { + EFI_IFR_STATEMENT_HEADER Header; + EFI_QUESTION_ID QuestionId; + EFI_VARSTORE_ID VarStoreId; + union { + EFI_STRING_ID VarName; + UINT16 VarOffset; + } VarStoreInfo; + UINT8 Flags; +} EFI_IFR_QUESTION_HEADER; + +Members: +Header The standard statement header. +QuestionId The unique value that identifies the particular question being defined by the opcode. The value of zero is reserved. +Flags A bit-mask that determines which unique settings are active for this question. +VarStoreId Specifies the identifier of a previously declared variable store to use when storing the question’s value. + A value of zero indicates no associated variable store. +VarStoreInfo If VarStoreId refers to Buffer Storage (EFI_IFR_VARSTORE or EFI_IFR_VARSTORE_EFI), then VarStoreInfo contains a 16-bit Buffer Storage offset (VarOffset). + If VarStoreId refers to Name/Value Storage (EFI_IFR_VARSTORE_NAME_VALUE), then VarStoreInfo contains the String ID of the name (VarName) for this name/value pair. + +Description +This is the standard header for questions. +``` + +# Creating `efivarstore` + + + +FS0:\> dmpstore -all +``` +Variable NV+BS 'EF2ACC91-7B50-4AB9-AB67-2B04F8BC135E:HIIFormCheckboxEfiVarstore' DataSize = 0x01 + 00000000: 01 *.* +``` + +FS0:\> dmpstore -guid EF2ACC91-7B50-4AB9-AB67-2B04F8BC135E +Variable NV+BS 'EF2ACC91-7B50-4AB9-AB67-2B04F8BC135E:HIIFormCheckboxEfiVarstore' DataSize = 0x01 + 00000000: 01 *.* |