1 files changed, 48 insertions, 43 deletions

diff --git a/zap/source/amd64/mem/memcp.S b/zap/source/amd64/mem/memcp.S
index 5691446..ac310ae 100644
--- a/zap/source/amd64/mem/memcp.S
+++ b/zap/source/amd64/mem/memcp.S
@@ -5,90 +5,95 @@
 .globl zap_memcp
 
 zap_memcp:
-	# rdi:  Address of the current input element.
-	# rsi:  Number of remaining elements.
-	# rdx:  Address of the current output element.
-	# rcx:  Current element.
-	# xmm0: Current element.
-	# ymm0: Current element.
+# Address of the current input element:
+#define iaddr %rdi
+# Number of remaining bytes:
+#define rem   %rsi
+# Address of the current output element:
+#define oaddr %rdx
+# Current element:
+#define val1  %cl
+#define val8  %rcx
+#define val01 %xmm0
+#define val02 %ymm0
 
 #if defined(__AVX__)
 	# AVX support 256-bit moves.
 
 	# Copy 32 bytes:
-.big20cp:
+.big02cp:
 
 	# Check if there are at least 32 bytes remaining:
-	cmpq $0x20,%rsi
-	jl .big10cp # If not, skip to the 10 byte copying.
+	cmpq $0x20,rem # if (rem < 20)
+	jl .big01cp    # goto big01cp  // If not, skip to the 10 byte copying.
 
 	# Copy:
-	vmovups (%rdi),%ymm0 # Move into a register.
-	vmovups %ymm0,(%rdx) # And then back into memory.
+	vmovups (iaddr),val02 # val02 = *iaddr
+	vmovups val02,(oaddr) # *oaddr = val02
 
 	# Continue:
-	addq $0x20,%rdi
-	addq $0x20,%rdx
-	subq $0x20,%rsi
-	jmp .big20cp
+	addq $0x20,iaddr # iaddr += 0x20
+	addq $0x20,oaddr # oaddr += 0x20
+	subq $0x20,rem   # rem -= 0x20
+	jmp .big02cp     # goto big02cp
 
 #endif
 
-	# AMD64 requires SSE(2).
+	# AMD64 requires SSE(2), so we don't have to test it.
 
 	# Copy 16 bytes:
-.big10cp:
+.big01cp:
 
 	# Check if there are at least 16 bytes remaining:
-	cmpq $0x10,%rsi
-	jl .wrdcp
+	cmpq $0x10,rem # if (rem < 10)
+	jl .wrdcp      # goto wrdcp
 
 	# Copy:
-	movdqu (%rdi),%xmm0
-	movdqu %xmm0,(%rdx)
+	movdqu (iaddr),val01 # val01 = *iaddr
+	movdqu val01,(oaddr) # *oaddr = val01 
 
 	# Continue:
-	addq $0x10,%rdi
-	addq $0x10,%rdx
-	subq $0x10,%rsi
-	jmp .big10cp
+	addq $0x10,iaddr # iaddr += 0x10
+	addq $0x10,oaddr # oaddr += 0x10
+	subq $0x10,rem   # rem -= 0x10
+	jmp .big01cp     # goto big01cp
 
 	# Copy one word (8 bytes):
 .wrdcp:
 
 	# Check if there are at least 8 bytes remaining:
-	cmpq $0x8,%rsi
-	jl .bytecp
+	cmpq $0x8,rem # if (rem < 8)
+	jl .bytecp    # goto bytecp
 
 	# Copy:
-	movq (%rdi),%rcx
-	movq %rcx,(%rdx)
+	movq (iaddr),val8 # val8 = *iaddr
+	movq val8,(oaddr) # *oaddr = val8
 
 	# Continue:
-	addq $0x8,%rdi
-	addq $0x8,%rdx
-	subq $0x8,%rsi
-	jmp .wrdcp
+	addq $0x8,iaddr # iaddr += 0x8
+	addq $0x8,oaddr # oaddr += 0x8
+	subq $0x8,rem   # rem -= 0x8
+	jmp .wrdcp      # goto wrdcp
 
 	# Copy one byte:
 .bytecp:
 
 	# Check if we have any bytes remaining:
-	testq %rsi,%rsi
-	jz .done
+	testq rem,rem # if (rem == 0x0)
+	jz .done      # goto done
 
 	# Copy:
-	movb (%rdi),%cl
-	movb %cl,(%rdx)
+	movb (iaddr),val1 # val1 = *iaddr
+	movb val1,(oaddr) # *oaddr = val1
 
 	# Continue:
-	incq %rdi
-	incq %rdx
-	decq %rsi
-	jmp .bytecp
+	incq iaddr  # ++iaddr
+	incq oaddr  # ++oaddr
+	decq rem    # --rem
+	jmp .bytecp # goto bytecp
 
-	# Finish:
+	# Return:
 .done:
 
-	ret
+	ret # return
 	
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