math,examples: add examples/sokol/sounds/simple_sin_tone_using_audio_push.v, cleanup math

cmd/tools/modules/testing/common.v

@@ -299,6 +299,7 @@ pub fn new_test_session(_vargs string, will_compile bool) TestSession {
 			skip_files << 'vlib/crypto/ecdsa/example/ensure_compatibility_with_net_openssl_test.v' // requires OpenSSL
 			// Fails compilation with: `/usr/bin/ld: /lib/x86_64-linux-gnu/libpthread.so.0: error adding symbols: DSO missing from command line`
 			skip_files << 'examples/sokol/sounds/simple_sin_tones.v'
+			skip_files << 'examples/sokol/sounds/simple_sin_tone_using_audio_push.v'
 		}
 		if github_job != 'misc-tooling' {
 			// These examples need .h files that are produced from the supplied .glsl files,

examples/sokol/sounds/simple_sin_tone_using_audio_push.v

@@ -0,0 +1,67 @@
+// import log
+import math
+import time
+import sokol.audio
+
+fn main() {
+	args := arguments()
+	freq := args[1] or { '417' }.int()
+	amplitude := args[2] or { '0.5' }.f32()
+	dump(freq)
+	dump(amplitude)
+
+	audio.setup(num_channels: 1)
+	sample_rate := dump(audio.sample_rate())
+	dump(audio.buffer_frames())
+	dump(audio.expect())
+
+	// create an array of frames, filled with the desired pure sine tone:
+	mut frames := []f32{len: sample_rate * 2} // 2 seconds
+	for i in 0 .. frames.len {
+		t := f32(i) / f32(sample_rate)
+		frames[i] = amplitude * math.sinf(f32(freq) * t * (2 * math.pi))
+	}
+
+	// play the sound by continuosly pushing samples from the generated
+	// array of sound frames, when there is need for more:
+	mut fpos := 0
+	for {
+		expected_frames := audio.expect()
+		if expected_frames > 0 {
+			written_frames := audio.push(unsafe { &frames[fpos] }, expected_frames)
+			fpos += written_frames
+			// log.info('> pushing done ... fpos: ${fpos:6} | expected_frames: ${expected_frames:6} | written: ${written:6}')
+			if fpos > frames.len - 2 * written_frames {
+				// log.info('> fpos too large: ${fpos}')
+				fpos = find_loop_position(fpos, frames)
+				// log.info('> fpos looped back to start: ${fpos}')
+			}
+		}
+		time.sleep(50 * time.millisecond)
+	}
+	audio.shutdown()
+}
+
+fn find_loop_position(fpos int, frames []f32) int {
+	return find_matching_position(frames, fpos, 0.01, 2) or {
+		find_matching_position(frames, fpos, 0.05, 2) or {
+			find_matching_position(frames, fpos, 0.1, 2) or { 0 }
+		}
+	}
+}
+
+@[direct_array_access]
+fn find_matching_position(frames []f32, fpos int, tol f32, d int) ?int {
+	if fpos - d < 0 || fpos + d >= frames.len {
+		return none
+	}
+	p1, p2, p3 := frames[fpos - d], frames[fpos], frames[fpos + d]
+	for i in 2 .. fpos / 2 {
+		np1, np2, np3 := frames[i - d], frames[i], frames[i + d]
+		if math.tolerance(np1, p1, tol) && math.tolerance(np2, p2, tol)
+			&& math.tolerance(np3, p3, tol) {
+			return i
+		}
+	}
+	return none
+}

vlib/math/gamma.v

@@ -1,5 +1,13 @@
 module math
 
+fn is_neg_int(x f64) bool {
+	if x < 0 {
+		_, xf := modf(x)
+		return xf == 0
+	}
+	return false
+}
+
 // gamma function computed by Stirling's formula.
 // The pair of results must be multiplied together to get the actual answer.
 // The multiplication is left to the caller so that, if careful, the caller can avoid

vlib/math/math.v

@@ -166,23 +166,23 @@ pub fn signbit(x f64) bool {
 	return f64_bits(x) & sign_mask != 0
 }
 
-// tolerance checks if a and b difference are less than or equal to the tolerance value
-pub fn tolerance(a f64, b f64, tol f64) bool {
-	mut ee := tol
-	// Multiplying by ee here can underflow denormal values to zero.
-	// Check a==b so that at least if a and b are small and identical
-	// we say they match.
-	if a == b {
+// tolerance checks if the difference between `actual` and `expected` numbers, is less than or equal to the tolerance value `tol`.
+// Note: the `actual` and `expected` parameters are NOT symmetrical.
+// If you compare against a known expected number, put it in the *second* argument, especially if it is 0.
+pub fn tolerance(actual f64, expected f64, tol f64) bool {
+	// Check actual==expected so that at least if they both are small and identical we say they match.
+	if actual == expected {
 		return true
 	}
-	mut d := a - b
+	mut d := actual - expected
 	if d < 0 {
 		d = -d
 	}
-	// note: b is correct (expected) value, a is actual value.
-	// make error tolerance a fraction of b, not a.
-	if b != 0 {
-		ee = ee * b
+	mut ee := tol
+	// make error tolerance a fraction of expected, not actual.
+	if expected != 0 {
+		// Multiplying by ee here can underflow denormal values to zero.
+		ee *= expected
 		if ee < 0 {
 			ee = -ee
 		}
@@ -190,14 +190,18 @@ pub fn tolerance(a f64, b f64, tol f64) bool {
 	return d < ee
 }
 
-// close checks if a and b are within 1e-14 of each other
-pub fn close(a f64, b f64) bool {
-	return tolerance(a, b, 1e-14)
+// close checks if `actual` and `expected` are within 1e-14 of each other
+// Note: the `actual` and `expected` parameters are NOT symmetrical.
+// If you compare against a known expected number, put it in the *second* argument, especially if it is 0.
+pub fn close(actual f64, expected f64) bool {
+	return tolerance(actual, expected, 1e-14)
 }
 
 // veryclose checks if a and b are within 4e-16 of each other
-pub fn veryclose(a f64, b f64) bool {
-	return tolerance(a, b, 4e-16)
+// Note: the `actual` and `expected` parameters are NOT symmetrical.
+// If you compare against a known expected number, put it in the *second* argument, especially if it is 0.
+pub fn veryclose(actual f64, expected f64) bool {
+	return tolerance(actual, expected, 4e-16)
 }
 
 // alike checks if a and b are equal
@@ -221,16 +225,3 @@ pub fn alike(a f64, b f64) bool {
 	}
 	return false
 }
-
-fn is_odd_int(x f64) bool {
-	xi, xf := modf(x)
-	return xf == 0 && (i64(xi) & 1) == 1
-}
-
-fn is_neg_int(x f64) bool {
-	if x < 0 {
-		_, xf := modf(x)
-		return xf == 0
-	}
-	return false
-}

vlib/math/pow.v

@@ -69,6 +69,11 @@ pub fn powi(a i64, b i64) i64 {
 	return v
 }
 
+fn is_odd_int(x f64) bool {
+	xi, xf := modf(x)
+	return xf == 0 && (i64(xi) & 1) == 1
+}
+
 // pow returns the base x, raised to the provided power y. (float64)
 //
 // todo(playXE): make this function work on JS backend, probably problem of JS codegen that it does not work.