X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?a=blobdiff_plain;f=src%2Flibc%2Fstring_asm.s;h=a15a405adc1e00212cad14a7c1b9ba2355714310;hb=22dd4db1a4ff756f76bdd87062c2252fe3091228;hp=7bb6f40bebe20bc76ddeb1b6d4f1853ba13b71ea;hpb=5a961b914da78d534e8e2dc6bfb5103114dbff54;p=bootcensus

diff --git a/src/libc/string_asm.s b/src/libc/string_asm.s
index 7bb6f40..a15a405 100644
--- a/src/libc/string_asm.s
+++ b/src/libc/string_asm.s
@@ -22,6 +22,7 @@ memset:
 	push %edi
 
 	mov 8(%ebp), %edi
+	push %edi
 	mov 12(%ebp), %al
 	mov %al, %ah
 	mov %ax, %cx
@@ -32,25 +33,29 @@ memset:
 	cmp $0, %ecx
 	jz msdone
 
+	# write 1, 2, or 3 times until we reache a 32bit-aligned dest address
 	mov %edi, %edx
 	and $3, %edx
+	jz msmain
 	jmp *mspre_tab(,%edx,4)
 
 mspre_tab: .long msmain, mspre1, mspre2, mspre3
-mspre1:	stosb
+mspre3:	stosb
 	dec %ecx
 mspre2:	stosb
 	dec %ecx
-mspre3:	stosb
+mspre1:	stosb
 	dec %ecx
 	jz msdone
 
+	# edi is 32bit-aligned here, write ecx>>2 32bit values
 msmain:
 	push %ecx
 	shr $2, %ecx
 	rep stosl
 	pop %ecx
 
+	# write any trailing bytes
 	and $3, %ecx
 	jmp *mspost_tab(,%ecx,4)
 
@@ -60,6 +65,7 @@ mspost2:stosb
 mspost1:stosb
 
 msdone:
+	pop %eax
 	pop %edi
 	pop %ebp
 	ret
@@ -74,6 +80,7 @@ memset16:
 	push %edi
 
 	mov 8(%ebp), %edi
+	push %edi
 	mov 12(%ebp), %ax
 	shl $16, %eax
 	mov 12(%ebp), %ax
@@ -84,6 +91,7 @@ memset16:
 
 	mov %edi, %edx
 	and $3, %edx
+	jz ms16main
 	jmp *ms16pre_tab(,%edx,4)
 
 ms16pre_tab: .long ms16main, ms16pre1, ms16pre2, ms16pre3
@@ -125,7 +133,7 @@ ms16main:
 	jz ms16done
 	stosw
 ms16done:
-
+	pop %eax
 	pop %edi
 	pop %ebp
 	ret
@@ -145,27 +153,12 @@ memcpy:
 	cmp $0, %ecx
 	jz mcdone
 
-	mov %edi, %edx
-	and $3, %edx
-	jmp *mcpre_tab(,%edx,4)
-
-mcpre_tab: .long mcmain, mcpre1, mcpre2, mcpre3
-mcpre1:	movsw
-	dec %ecx
-mcpre2:	movsw
-	dec %ecx
-mcpre3:	movsw
-	dec %ecx
-	jz mcdone
-
-mcmain:
-	push %ecx
+	mov %ecx, %edx
 	shr $2, %ecx
 	rep movsl
-	pop %ecx
 
-	and $3, %ecx
-	jmp *mcpost_tab(,%ecx,4)
+	and $3, %edx
+	jmp *mcpost_tab(,%edx,4)
 
 mcpost_tab: .long mcdone, mcpost1, mcpost2, mcpost3
 mcpost3:movsb