drop float16 dependency

goos: darwin
goarch: arm64
pkg: github.com/ollama/ollama/convert/float16
cpu: Apple M3 Max
BenchmarkFloat16/x448/float16-16                     159           7398462 ns/op
BenchmarkFloat16/simple-16                           512           2327098 ns/op
PASS
ok      github.com/ollama/ollama/convert/float16        2.553s

convert/float16/float16.go

@@ -0,0 +1,97 @@
+package float16
+
+import (
+	"math"
+)
+
+func FromFloat32s(f32s []float32) (u16s []uint16) {
+	u16s = make([]uint16, len(f32s))
+	for i := range f32s {
+		bits := math.Float32bits(f32s[i])
+		sign := (bits >> 31) & 0x1
+		exponent := (bits >> 23) & 0xFF
+		mantissa := bits & 0x7FFFFF
+		if exponent == 0xFF {
+			if mantissa == 0 {
+				// Infinity
+				u16s[i] = uint16((sign << 15) | 0x7C00)
+			} else {
+				// NaN
+				u16s[i] = uint16((sign << 15) | 0x7C00 | (mantissa >> 13))
+			}
+		} else if exponent == 0 && mantissa == 0 {
+			// Zero
+			u16s[i] = uint16(sign << 15)
+		} else {
+			// Convert exponent from FP32 bias (127) to FP16 bias (15)
+			exponent := int(exponent) - 127 + 15
+			if exponent >= 31 {
+				// Overflow to infinity
+				u16s[i] = uint16((sign << 15) | 0x7C00)
+			} else if exponent <= 0 {
+				// Underflow - create subnormal or zero
+				if exponent < -10 {
+					u16s[i] = uint16(sign << 15) // Zero
+				} else {
+					// Subnormal number
+					mantissa = (mantissa | 0x800000) >> uint(-exponent+1)
+					u16s[i] = uint16((sign << 15) | (mantissa >> 13))
+				}
+			} else {
+				// Normal number - truncate mantissa from 23 to 10 bits
+				u16s[i] = uint16((sign << 15) | (uint32(exponent) << 10) | (mantissa >> 13))
+			}
+		}
+	}
+
+	return u16s
+}
+
+func Float32s(u16s []uint16) (f32s []float32) {
+	f32s = make([]float32, len(u16s))
+	for i := range u16s {
+		sign := (u16s[i] >> 15) & 0x1
+		exponent := (u16s[i] >> 10) & 0x1F
+		mantissa := u16s[i] & 0x3FF
+
+		var u32 uint32
+		switch exponent {
+		case 0:
+			if mantissa == 0 {
+				// Zero
+				u32 = uint32(sign) << 31
+			} else {
+				// Subnormal - convert to normal
+				// Find leading 1 bit
+				shift := 0
+				temp := mantissa
+				for temp&0x400 == 0 {
+					temp <<= 1
+					shift++
+				}
+
+				exponent := 127 - 15 + 1 - shift
+				mantissa := (uint32(temp&0x3FF) << 13)
+
+				u32 = (uint32(sign) << 31) | (uint32(exponent) << 23) | mantissa
+			}
+		case 0x1F:
+			if mantissa == 0 {
+				// Infinity
+				u32 = (uint32(sign) << 31) | 0x7F800000
+			} else {
+				// NaN
+				u32 = (uint32(sign) << 31) | 0x7F800000 | (uint32(mantissa) << 13)
+			}
+		default:
+			// Normal number
+			exponent := uint32(exponent) - 15 + 127
+			mantissa := uint32(mantissa) << 13
+
+			u32 = (uint32(sign) << 31) | (exponent << 23) | mantissa
+		}
+
+		f32s[i] = math.Float32frombits(u32)
+	}
+	return f32s
+}