#include "config.h"
+#define PROTECTED_MODE_CS (2 << 3) // 0x10
+#define PROTECTED_MODE_DS (3 << 3) // 0x18
+#define REAL_MODE_CS (4 << 3) // 0x20
+#define REAL_MODE_DS (5 << 3) // 0x28
+
.code16gcc
- .text
+
+
+/****************************************************************
+ * Include of 16bit C code
+ ****************************************************************/
+
.globl bios16c_start, bios16c_end
bios16c_start:
.include "out/blob.proc.16.s"
bios16c_end:
+/****************************************************************
+ * Entry macros
+ ****************************************************************/
+
+ // Call a C function - this does the minimal work necessary to
+ // call into C. It sets up %ds, backs up %es, and backs up
+ // those registers that are call clobbered by the C compiler.
+ .macro ENTRY cfunc
+ cld
+ pushl %eax
+ pushl %ecx
+ pushl %edx
+ pushw %es
+ pushw %ds
+ movw %ss, %ax
+ movw %ax, %ds
+ calll \cfunc
+ popw %ds
+ popw %es
+ popl %edx
+ popl %ecx
+ popl %eax
+ .endm
+
+ // Call a C function with current register list as an
+ // argument. This backs up the registers and sets %eax
+ // to point to the backup. On return, the registers are
+ // restored from the structure.
+ .macro ENTRY_ARG cfunc
+ cld
+ pushl %eax
+ pushl %ecx
+ pushl %edx
+ pushl %ebx
+ pushl %esi
+ pushl %edi
+ pushw %es
+ pushw %ds
+ movw %ss, %ax
+ movw %ax, %ds
+ movzwl %sp, %esp
+ movl %esp, %eax
+ calll \cfunc
+ popw %ds
+ popw %es
+ popl %edi
+ popl %esi
+ popl %ebx
+ popl %edx
+ popl %ecx
+ popl %eax
+ .endm
+
+ // Macro to reset the 16bit stack
+ // Clobbers %ax
+ .macro RESET_STACK
+ xorw %ax, %ax
+ movw %ax, %ss
+ movl $ CONFIG_STACK_OFFSET , %esp
+ .endm
+
+
+/****************************************************************
+ * POST handler
+ ****************************************************************/
+
.org 0xe05b
- .globl _start
-_start:
.globl post16
post16:
+ // init the stack pointer
+ RESET_STACK
- // Entry point of rombios32 code - the actual instruction is
- // altered later in the build process.
+ // Set entry point of rombios32 code - the actual address
+ // is altered later in the build process.
.globl set_entry32
set_entry32:
- mov $0xf0000000, %ebx
+ pushl $0xf0000000
- // init the stack pointer
- movl $ CONFIG_STACK32_OFFSET , %esp
+ cld
+ // Fall through to transition32 function below
+
+
+/****************************************************************
+ * Call trampolines
+ ****************************************************************/
+
+// Place CPU into 32bit mode from 16bit mode.
+// Clobbers: %eax, flags, stack registers, cr0, idt/gdt
transition32:
// Disable irqs
cli
movl %eax, %cr0
// start protected mode code
- .word 0xea66, 1f, 0x000f, 0x0010 // ljmpl $0x10, $(post32 | 0xf0000)
+ // ljmpl $PROTECTED_MODE_CS, $(1f | 0xf0000)
+ .word 0xea66, 1f, 0x000f, PROTECTED_MODE_CS
.code32
1:
// init data segments
- movl $0x18, %eax
+ movl $PROTECTED_MODE_DS, %eax
movw %ax, %ds
movw %ax, %es
movw %ax, %ss
movw %ax, %fs
movw %ax, %gs
- cld
-
- jmp *%ebx
+ retl
- .code16gcc
-
-// We need a copy of this string, but we are not actually a PnP BIOS,
-// so make sure it is *not* aligned, so OSes will not see it if they
-// scan.
- .align 2
- .byte 0
-pnp_string:
- .ascii "$PnP"
+// Call a 16bit function from 32bit mode.
+// %eax = address of struct bregs
+// Clobbers: all gp registers, flags, stack registers, cr0, idt/gdt
+ .globl __call16_from32
+__call16_from32:
+ pushl %eax
-// Return from 32bit code to 16bit code - must pass in destination
-// code segment,offset (%ebx) and the return stack position (%esp).
+ // Jump to 16bit mode
+ ljmp $REAL_MODE_CS, $1f
- .globl call16
-call16:
+ .code16gcc
+1:
// restore data segment limits to 0xffff
- movw $0x28, %ax
+ movw $REAL_MODE_DS, %ax
movw %ax, %ds
movw %ax, %es
movw %ax, %ss
movl %eax, %cr0
// far jump to flush CPU queue after transition to real mode
- ljmpw $0xf000, $1f
-1:
+ ljmpw $0xf000, $2f
+
+2:
// restore IDT to normal real-mode defaults
lidt %cs:rmode_IDT_info
- // Setup segment registers
+ // Clear segment registers
xorw %ax, %ax
- movw %ax, %ds
movw %ax, %fs
movw %ax, %gs
- movw $0xf000, %ax
movw %ax, %es
- lea pnp_string, %di
- movw $ CONFIG_STACK16_SEGMENT , %ax
- movw %ax, %ss
- movl %esp, %eax
- movl $ CONFIG_STACK16_OFFSET , %esp
+ movw %ax, %ds
+ movw %ax, %ss // Assume stack is in segment 0
- // Save info
- pushl %eax
- pushl %ebx
- movl %esp, %ebp
+ popl %eax
+ pushl $transition32
+
+ // Fall through to __call16
- lcallw %ss:*(%bp)
- // Restore stack and jump back to 32bit mode.
+// Call a 16bit function from 16bit mode with a specified cpu register state
+// %eax = address of struct bregs
+// Clobbers: all gp registers, es
+ .globl __call16
+__call16:
+ // Save eax
+ pushl %eax
+
+ // Setup for iretw call
+ pushw $0xf000
+ pushw $1f // return point
+ pushw 0x20(%eax) // flags
+ pushl 0x1c(%eax) // CS:IP
+
+ // Load calling registers.
+ movl 0x04(%eax), %edi
+ movl 0x08(%eax), %esi
+ movl 0x0c(%eax), %ebx
+ movl 0x10(%eax), %edx
+ movl 0x14(%eax), %ecx
+ movw 0x02(%eax), %es // XXX - should load %ds too
+ movl 0x18(%eax), %eax
+
+ // Invoke call
+ iretw // XXX - just do a lcalll
+1:
+ // Store flags, eax, ecx
+ pushfw
+ pushl %eax
+ movl 0x06(%esp), %eax
+ movl %ecx, %ss:0x14(%eax) // Save %ecx
+ movw %ss, %cx
+ movw %cx, %ds // Restore %ds == %ss
+ popl %ecx
+ movl %ecx, 0x18(%eax) // Save %eax
+ popw %cx
+ movw %cx, 0x20(%eax) // Save flags
+
+ // Store remaining registers
+ movw %es, 0x02(%eax)
+ movl %edi, 0x04(%eax)
+ movl %esi, 0x08(%eax)
+ movl %ebx, 0x0c(%eax)
+ movl %edx, 0x10(%eax)
+
+ // Remove %eax
popl %eax
- popl %esp
- // Resume point of rombios32 code - the actual instruction is
- // altered later in the build process.
- .globl set_resume32
-set_resume32:
- mov $0xf0000000, %ebx
+ cld
+
+ retl
- jmp transition32
+ // APM trampolines
+ .globl apm16protected_entry
+apm16protected_entry:
+ pushfw // save flags
+ pushl %eax // dummy
+ ENTRY_ARG handle_1553
+ addw $4, %sp // pop dummy
+ popfw // restore flags
+ lretw
+ .code32
+ .globl apm32protected_entry
+apm32protected_entry:
+ pushfw // save flags
+ pushw %cs // Setup for long jump to 16bitmode
+ incw (%esp)
+ pushw 1f
+ lcallw *(%esp)
+ addl $4, %esp // pop call address
+ popfw
+ lretl
+ .code16gcc
+1: // 16bit entry point for apm32 code.
+ ENTRY_ARG handle_1553
+ lretw
+
+
+/****************************************************************
+ * GDT and IDT tables
+ ****************************************************************/
// Protected mode IDT descriptor
//
// Set limit to 0
pmode_IDT_info:
.word 0x0000 // limit 15:00
- .word 0x0000 // base 15:00
- .byte 0x0f // base 23:16
+ .long 0xf0000 // base 16:47
// Real mode IDT descriptor
//
// limit = 03ff
rmode_IDT_info:
.word 0x03ff // limit 15:00
- .word 0x0000 // base 15:00
- .byte 0x00 // base 23:16
+ .long 0 // base 16:47
rombios32_gdt_48:
.word 0x30
.word rombios32_gdt
.word 0x000f
+ .balign 8
rombios32_gdt:
.word 0, 0, 0, 0
.word 0, 0, 0, 0
- .word 0xffff, 0, 0x9b00, 0x00cf // 32 bit flat code segment (0x10)
- .word 0xffff, 0, 0x9300, 0x00cf // 32 bit flat data segment (0x18)
- .word 0xffff, 0, 0x9b0f, 0x0000 // 16 bit code segment base=0xf0000 limit=0xffff
- .word 0xffff, 0, 0x9300, 0x0000 // 16 bit data segment base=0x0 limit=0xffff
+ // 32 bit flat code segment (PROTECTED_MODE_CS)
+ .word 0xffff, 0, 0x9b00, 0x00cf
+ // 32 bit flat data segment (PROTECTED_MODE_DS)
+ .word 0xffff, 0, 0x9300, 0x00cf
+ // 16 bit code segment base=0xf0000 limit=0xffff (REAL_MODE_CS)
+ .word 0xffff, 0, 0x9b0f, 0x0000
+ // 16 bit data segment base=0x0 limit=0xffff (REAL_MODE_DS)
+ .word 0xffff, 0, 0x9300, 0x0000
- .macro ENTRY cfunc
- pushal
- pushw %es
- pushw %ds
- movw %ss, %ax
- movw %ax, %ds
- mov %esp, %eax
- call \cfunc
- popw %ds
- popw %es
- popal
- .endm
+/****************************************************************
+ * Interrupt entry points
+ ****************************************************************/
+ // Define an entry point for an interrupt (no args passed).
.macro IRQ_ENTRY num
.globl entry_\num
entry_\num :
+ cli // In case something far-calls instead of using "int"
ENTRY handle_\num
iretw
.endm
+ // Define an entry point for an interrupt (can read/modify args).
+ .macro IRQ_ENTRY_ARG num
+ .globl entry_\num
+ entry_\num :
+ cli // In case something far-calls instead of using "int"
+ ENTRY_ARG handle_\num
+ iretw
+ .endm
.org 0xe2c3
IRQ_ENTRY nmi
- IRQ_ENTRY 13
- IRQ_ENTRY 19
- IRQ_ENTRY 12
- IRQ_ENTRY 11
+ IRQ_ENTRY_ARG 13
+ IRQ_ENTRY_ARG 12
+ IRQ_ENTRY_ARG 11
IRQ_ENTRY 76
- IRQ_ENTRY 18
IRQ_ENTRY 1c
IRQ_ENTRY 70
IRQ_ENTRY 74
- IRQ_ENTRY 75
.org 0xe3fe
jmp entry_13
// XXX - Baud Rate Generator Table
.org 0xe739
- IRQ_ENTRY 14
+ IRQ_ENTRY_ARG 14
+
+ IRQ_ENTRY 75
+
+ // int 18/19 are special - they reset the stack and do not return.
+ .globl entry_19
+entry_19:
+ RESET_STACK
+ ENTRY handle_19
+
+ .globl entry_18
+entry_18:
+ RESET_STACK
+ ENTRY handle_18
+
+ // IRQ trampolines
+ .macro IRQ_TRAMPOLINE num
+ .globl irq_trampoline_0x\num
+ irq_trampoline_0x\num :
+ int $0x\num
+ lretw
+ .endm
+
+ IRQ_TRAMPOLINE 02
+ IRQ_TRAMPOLINE 10
+ IRQ_TRAMPOLINE 13
+ IRQ_TRAMPOLINE 15
+ IRQ_TRAMPOLINE 18
+ IRQ_TRAMPOLINE 19
+ IRQ_TRAMPOLINE 1c
+ IRQ_TRAMPOLINE 4a
.org 0xe82e
- IRQ_ENTRY 16
+ IRQ_ENTRY_ARG 16
.org 0xe987
IRQ_ENTRY 09
.org 0xec59
- IRQ_ENTRY 40
+ IRQ_ENTRY_ARG 40
.org 0xef57
IRQ_ENTRY 0e
.org 0xefc7
- // XXX - Diskette Controller Parameter Table
+.include "out/floppy_dbt.proc.16.s"
+ .text
.org 0xefd2
- IRQ_ENTRY 17
+ IRQ_ENTRY_ARG 17
.org 0xf045
// XXX int 10
iretw
.org 0xf065
- IRQ_ENTRY 10
+ IRQ_ENTRY_ARG 10
.org 0xf0a4
// XXX int 1D
iretw
+ .globl freespace2_start, freespace2_end
+freespace2_start:
+
.org 0xf841
+freespace2_end:
jmp entry_12
.org 0xf84d
jmp entry_11
.org 0xf859
- IRQ_ENTRY 15
+ IRQ_ENTRY_ARG 15
.org 0xfa6e
.include "out/font.proc.16.s"
.text
.org 0xfe6e
- IRQ_ENTRY 1a
+ IRQ_ENTRY_ARG 1a
.org 0xfea5
IRQ_ENTRY 08
iretw
.org 0xff54
- IRQ_ENTRY 05
+ IRQ_ENTRY_ARG 05
.org 0xfff0 // Power-up Entry Point
ljmpw $0xf000, $post16
.ascii "06/23/99"
.org 0xfffe
- // model byte 0xFC = AT
- .byte 0xfc
+ .byte CONFIG_MODEL_ID
.byte 0x00
.end
projects / seabios.git / blobdiff