Revert "decompressor: Use as instead of nasm"

This reverts commit 39559b39ff.

decompressor/GNUmakefile

@@ -52,8 +52,8 @@ override INTERNAL_LDFLAGS := \
 	-Tlinker.ld
 
 override C_FILES := $(shell find ./ -type f -name '*.c')
-override ASM_FILES := $(shell find ./ -type f -name '*.S')
-override OBJ := $(addprefix $(call MKESCAPE,$(BUILDDIR))/, $(ASM_FILES:.S=.o) $(C_FILES:.c=.o))
+override ASM_FILES := $(shell find ./ -type f -name '*.asm')
+override OBJ := $(addprefix $(call MKESCAPE,$(BUILDDIR))/, $(ASM_FILES:.asm=.o) $(C_FILES:.c=.o))
 override HEADER_DEPS := $(addprefix $(call MKESCAPE,$(BUILDDIR))/, $(C_FILES:.c=.d))
 
 .PHONY: all
@@ -83,9 +83,9 @@ $(call MKESCAPE,$(BUILDDIR))/%.o: %.c $(call MKESCAPE,$(BUILDDIR))/tinf-copied
 	mkdir -p "$$(dirname '$(call SHESCAPE,$@)')"
 	$(LIMINE_CC) $(LIMINE_CFLAGS) -Os $(INTERNAL_CFLAGS) -c '$(call SHESCAPE,$<)' -o '$(call SHESCAPE,$@)'
 
-$(call MKESCAPE,$(BUILDDIR))/%.o: %.S
+$(call MKESCAPE,$(BUILDDIR))/%.o: %.asm
 	mkdir -p "$$(dirname '$(call SHESCAPE,$@)')"
-	$(LIMINE_CC) $(LIMINE_CFLAGS) -Os $(INTERNAL_CFLAGS) -c '$(call SHESCAPE,$<)' -o '$(call SHESCAPE,$@)'
+	nasm '$(call SHESCAPE,$<)' -f elf32 -o '$(call SHESCAPE,$@)'
 
 .PHONY: clean
 clean:

decompressor/entry.S

@@ -1,14 +0,0 @@
-.section .entry
-
-.globl _start
-_start:
-    cld
-
-    // Zero out .bss
-    xor %al, %al
-    mov $bss_begin, %edi
-    mov $bss_end, %ecx
-    sub $bss_begin, %ecx
-    rep stosb
-
-    jmp entry

decompressor/entry.asm

@@ -0,0 +1,18 @@
+extern bss_begin
+extern bss_end
+extern entry
+
+section .entry
+
+global _start
+_start:
+    cld
+
+    ; Zero out .bss
+    xor al, al
+    mov edi, bss_begin
+    mov ecx, bss_end
+    sub ecx, bss_begin
+    rep stosb
+
+    jmp entry