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Bootloader: Optimize some unnecessary branches on carry add/sub

This commit is contained in:
Bananymous 2024-01-03 17:05:33 +02:00
parent 2a68df81e2
commit 7356a83a44
2 changed files with 4 additions and 9 deletions
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10
bootloader/bios/disk.S
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@ -389,10 +389,8 @@ find_root_partition:
# increment 8 byte entry array lba
incl 0(%esp)
jnc .find_root_partition_no_overflow
incl 4(%esp)
adcl $0, 4(%esp)
.find_root_partition_no_overflow:
# loop to read next section if entries remaining
cmpl $0, 12(%esp)
jnz .find_root_partition_read_entry_section
@ -416,12 +414,10 @@ find_root_partition:
# ebx:eax -= first lba - 1
subl (root_partition_entry + 36), %ebx
movl (root_partition_entry + 32), %ecx;
movl (root_partition_entry + 32), %ecx
decl %ecx
subl %ecx, %eax
jnc .find_root_partition_count_sub_no_carry
decl %ebx
.find_root_partition_count_sub_no_carry:
sbbl $0, %ebx
# ecx: min(partition count, 0xFFFFFFFF)
movl $0xFFFFFFFF, %edx

3
bootloader/bios/framebuffer.S
View File

@ -95,8 +95,7 @@ vesa_find_video_mode:
cmpw $0x0200, (vesa_info_buffer + 0x04)
jb .vesa_unsupported_version
movl $(vesa_info_buffer + 0x0E), %esi
movl (%esi), %esi
movl (vesa_info_buffer + 0x0E), %esi
.vesa_find_video_mode_loop_modes:
cmpw $0xFFFF, (%esi)
je .vesa_find_video_mode_loop_modes_done