1 files changed, 171 insertions, 0 deletions
diff --git a/zap/src/fma.c b/zap/src/fma.c
new file mode 100644
index 0000000..b2f45ad
--- /dev/null
+++ b/zap/src/fma.c
@@ -0,0 +1,171 @@
+/*
+	Copyright 2022 Gabriel Jensen.
+	This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
+	If a copy of the MPL was not distributed with this file, You can obtain one at https://mozilla.org/MPL/2.0/.
+*/
+
+#include <zap/priv.h>
+
+#include <zap/math.h>
+
+#include <stdint.h>
+
+#if zap_priv_fastimpl
+__asm__ (
+	".globl zap_fma_c\n"
+	".globl zap_fma_i\n"
+	".globl zap_fma_l\n"
+	".globl zap_fma_ll\n"
+	".globl zap_fma_s\n"
+	".globl zap_fma_uc\n"
+	".globl zap_fma_ui\n"
+	".globl zap_fma_ul\n"
+	".globl zap_fma_ull\n"
+	".globl zap_fma_us\n"
+
+	"zap_fma_c:\n"
+		/*
+			signed char a
+			signed char b
+			signed char c
+		*/
+#if defined(sus_arch_amd64)
+		"movb %sil,%al\n"
+		"imulb %dl\n"
+		"addb %dil,%al\n"
+		"ret\n"
+#endif
+
+	"zap_fma_i:\n"
+		/*
+			int a
+			int b
+			int c
+		*/
+#if defined(sus_arch_amd64)
+		"movl %edx,%eax\n"
+		"imull %esi\n"
+		"addl %edi,%eax\n"
+		"ret\n"
+#endif
+
+	"zap_fma_l:\n"
+		/*
+			long a
+			long b
+			long c
+		*/
+#if defined(sus_arch_amd64)
+		"movq %rdx,%rax\n"
+		"imulq %rsi\n"
+		"addq %rdi,%rax\n"
+		"ret\n"
+#endif
+
+	"zap_fma_ll:\n"
+		/*
+			long long a
+			long long b
+			long long c
+		*/
+#if defined(sus_arch_amd64)
+		"movq %rdx,%rax\n"
+		"imulq %rsi\n"
+		"addq %rdi,%rax\n"
+		"ret\n"
+#endif
+
+	"zap_fma_s:\n"
+		/*
+			short a
+			short b
+			short c
+		*/
+#if defined(sus_arch_amd64)
+		"movw %dx,%ax\n"
+		"imulw %si\n"
+		"addw %di,%ax\n"
+		"ret\n"
+#endif
+
+	"zap_fma_uc:\n"
+		/*
+			unsigned char a
+			unsigned char b
+			unsigned char c
+		*/
+#if defined(sus_arch_amd64)
+		"movb %sil,%al\n" /* mulb uses ax instead of al:dl (like the other variants), so we don't need to worry about it overwritting dl. */
+		"mulb %dl\n"
+		"addb %dil,%al\n"
+		"ret\n"
+#endif
+
+	"zap_fma_ui:\n"
+		/*
+			unsigned int a
+			unsigned int b
+			unsigned int c
+		*/
+#if defined(sus_arch_amd64)
+		"movl %edx,%eax\n"
+		"mull %esi\n"
+		"addl %edi,%eax\n"
+		"ret\n"
+#endif
+
+	"zap_fma_ul:\n"
+		/*
+			unsigned long a
+			unsigned long b
+			unsigned long c
+		*/
+#if defined(sus_arch_amd64)
+		"movq %rdx,%rax\n"
+		"mulq %rsi\n"
+		"addq %rdi,%rax\n"
+		"ret\n"
+#endif
+
+	"zap_fma_ull:\n"
+		/*
+			unsigned long long a
+			unsigned long long b
+			unsigned long long c
+		*/
+#if defined(sus_arch_amd64)
+		"movq %rdx,%rax\n" /* rdx get overwritten by mulq, so might as well just make it the first operand (in multiplication, the order is meaningless). */
+		"mulq %rsi\n"
+		"addq %rdi,%rax\n"
+		"ret\n"
+#endif
+
+	"zap_fma_us:\n"
+		/*
+			unsigned short a
+			unsigned short b
+			unsigned short c
+		*/
+#if defined(sus_arch_amd64)
+		"movw %dx,%ax\n"
+		"mulw %si\n"
+		"addw %di,%ax\n"
+		"ret\n"
+#endif
+);
+#else
+#define zap_local_fma(_typ,_sufx) \
+	_typ zap_fma_ ## _sufx (_typ const _a,_typ const _b,_typ const _c) {return _a + _b * _c;}
+
+zap_local_fma(signed char,c)
+zap_local_fma(int,i)
+zap_local_fma(long,l)
+zap_local_fma(long long,ll)
+zap_local_fma(short,s)
+zap_local_fma(unsigned char,uc)
+zap_local_fma(unsigned int,ui)
+zap_local_fma(unsigned long,ul)
+zap_local_fma(unsigned long long,ull)
+zap_local_fma(unsigned short,us)
+
+#endif