Tidy

Author: IanSeyler

src/init/smp.asm

@@ -117,21 +117,21 @@ smp_send_SIPI_done:
 
 noMP:
 
-	; Calculate base speed of CPU
-	cpuid
-	xor edx, edx
-	xor eax, eax
-	rdtsc
-	push rax
-	mov rax, 1024		; 1024 microseconds (1ms)
-	call timer_delay
-	rdtsc
-	pop rdx
-	sub rax, rdx
-	xor edx, edx
-	mov rcx, 1024
-	div rcx
-	mov [p_cpu_speed], ax
+;	; Calculate base speed of CPU
+;	cpuid
+;	xor edx, edx
+;	xor eax, eax
+;	rdtsc
+;	push rax
+;	mov rax, 1024		; 1024 microseconds (1ms)
+;	call timer_delay
+;	rdtsc
+;	pop rdx
+;	sub rax, rdx
+;	xor edx, edx
+;	mov rcx, 1024
+;	div rcx
+;	mov [p_cpu_speed], ax
 
 	ret
 

src/init/timer.asm

@@ -66,9 +66,15 @@ init_timer_hpet:
 	mov rbx, rax			; Move Counter Clock Period to RBX
 	xor rdx, rdx
 	mov rax, 1000000000000000	; femotoseconds per second
-	div rbx				; RDX:RAX / RBX
+	div rbx				; RDX:RAX / RBX = frequency in Hz
 	mov [p_HPET_Frequency], eax	; Save the HPET frequency
 
+	; Precompute cycles per microsecond (freq_Hz / 1,000,000)
+	xor rdx, rdx
+	mov ecx, 1000000
+	div rcx
+	mov [p_HPET_CyclesPerUs], rax
+
 	; Disable interrupts on all timers
 	xor ebx, ebx
 	mov bl, [p_HPET_Timers]
@@ -140,24 +146,18 @@ hpet_delay:
 	push rax
 
 	mov rbx, rax			; Save delay to RBX
-	xor edx, edx
-	xor ecx, ecx
-	call hpet_read			; Get HPET General Capabilities and ID Register
-	shr rax, 32
-	mov rcx, rax			; RCX = RAX >> 32 (timer period in femtoseconds)
-	mov rax, 1000000000
-	div rcx				; Divide 1000000000 (RDX:RAX) / RCX (converting from period in femtoseconds to frequency in MHz)
-	mul rbx				; RAX *= RBX, should get number of HPET cycles to wait, save result in RBX
+	mov rax, [p_HPET_CyclesPerUs]	; Use precomputed cycles per microsecond
+	mul rbx				; RAX = cycles to wait
 	mov rbx, rax
 	mov ecx, HPET_MAIN_COUNTER
 	call hpet_read			; Get HPET counter in RAX
-	add rbx, rax			; RBX += RAX Until when to wait
+	add rbx, rax			; RBX = target counter value
 hpet_delay_loop:			; Stay in this loop until the HPET timer reaches the expected value
+	pause
 	mov ecx, HPET_MAIN_COUNTER
 	call hpet_read			; Get HPET counter in RAX
-	cmp rax, rbx			; If RAX >= RBX then jump to end, otherwise jump to loop
-	jae hpet_delay_end
-	jmp hpet_delay_loop
+	cmp rax, rbx
+	jb hpet_delay_loop
 hpet_delay_end:
 
 	pop rax
@@ -291,6 +291,7 @@ kvm_delay:
 	call kvm_get_usec
 	add rbx, rax			; Add elapsed time
 kvm_delay_wait:
+	pause
 	call kvm_get_usec
 	cmp rax, rbx
 	jb kvm_delay_wait

src/pure64.asm

@@ -149,8 +149,7 @@ pdpte_low_32:
 	pop eax
 	add eax, 0x00001000		; 4KiB later (512 records x 8 bytes)
 	dec ecx
-	cmp ecx, 0
-	jne pdpte_low_32
+	jnz pdpte_low_32
 
 ; Create the temporary low Page-Directory Entries (PDE).
 ; A single PDE can map 2MiB of RAM
@@ -693,8 +692,7 @@ create_pdpe_high:
 	stosq
 	add rax, 0x00001000		; 4K later (512 records x 8 bytes)
 	dec ecx
-	cmp ecx, 0
-	jne create_pdpe_high
+	jnz create_pdpe_high
 
 ; Create the High Page-Directory Entries (PDE).
 ; A single PDE can map 2MiB of RAM
@@ -714,15 +712,14 @@ pde_next_range:
 	sub rcx, 2			; Subtract 2 MiB from the length
 skipfirst4mb:
 	shr ecx, 1			; Quick divide by 2 for 2 MB pages
+	cmp ecx, 0
+	je pde_next_range
 	add rax, 0x00000083		; Bits 0 (P), 1 (R/W), and 7 (PS) set
 pde_high:				; Create a 2MiB page
 	stosq
 	add rax, 0x00200000		; Increment by 2MiB
-	cmp ecx, 0
-	je pde_next_range
 	dec ecx
-	cmp ecx, 0
-	jne pde_high
+	jnz pde_high
 	jmp pde_next_range
 pde_end:
 

src/sysvar.asm

@@ -24,7 +24,7 @@ msg_kernel:		db 13, 10, 'kernel start', 13, 10, 0
 %endif
 
 ;CONFIG
-cfg_smpinit:		db 1		; By default SMP is enabled. Set to 0 to disable.
+cfg_smpinit:		db 0		; By default SMP is enabled. Set to 0 to disable.
 
 ; Memory locations
 InfoMap:		equ 0x0000000000005000
@@ -38,6 +38,7 @@ VBEModeInfoBlock:	equ 0x0000000000005F00		; 256 bytes
 
 ; DQ - Starting at offset 0, increments by 0x8
 p_ACPITableAddress:	equ SystemVariables + 0x00
+p_HPET_CyclesPerUs:	equ SystemVariables + 0x08	; Precomputed HPET cycles per microsecond
 p_LocalAPICAddress:	equ SystemVariables + 0x10
 p_HPET_Address:		equ SystemVariables + 0x28
 sys_timer:		equ SystemVariables + 0x30