diff --git a/engine/drumkit.c b/engine/drumkit.c
index 97a4fdccee40d2a790d6a5c5bf10ab9d7d1618ab..0193446c1a3322c419229cd7deac716901f72b3f 100644
--- a/engine/drumkit.c
+++ b/engine/drumkit.c
@@ -13,6 +13,7 @@
#include "drumkit.h"
+// Set default values on an instrument.
static void instrument_set_defaults(struct instrument *ins) {
ins->pan_l = ins->pan_r = 1;
ins->gain = ins->volume = 1;
@@ -24,6 +25,7 @@ static void instrument_set_defaults(struct instrument *ins) {
ins->note = 0;
}
+// Return a sndfile format value in human-readable format.
static char *sf_format_name(int format) {
static char fmtbuf[32];
const char *major = "weird", *subtype = NULL;
@@ -52,6 +54,7 @@ static char *sf_format_name(int format) {
return fmtbuf;
}
+// Dump instrument metadata to standard output.
static void print_instrument(struct instrument *ins) {
int i;
printf("instrument %s: pan=%g/%g, gain=%g\n", ins->name, ins->pan_l,
@@ -64,8 +67,11 @@ static void print_instrument(struct instrument *ins) {
}
}
+// Return a string with the content of the result of an XPath
+// expression (which should evaluate the text() of a single node), or
+// NULL if the expression returned no nodes.
static const char *xpath_value_as_string(xmlNodePtr node, const char *xpathExpr,
- xmlXPathContextPtr xpathCtx) {
+ xmlXPathContextPtr xpathCtx) {
xmlXPathObjectPtr res;
const char *content;
res = xmlXPathNodeEval(node, (const xmlChar *)xpathExpr, xpathCtx);
@@ -80,6 +86,9 @@ static const char *xpath_value_as_string(xmlNodePtr node, const char *xpathExpr,
return content;
}
+// Evaluate an XPath expression and store the result as a float. The
+// value pointed by out won't be modified if the XPath expression has
+// no result.
static void xpath_get_float(float *out, xmlNodePtr node, const char *xpathExpr,
xmlXPathContextPtr xpathCtx) {
const char *s;
@@ -91,6 +100,9 @@ static void xpath_get_float(float *out, xmlNodePtr node, const char *xpathExpr,
*out = strtof(s, NULL);
}
+// Evaluate an XPath expression and store the result as an
+// integer. The value pointed by out won't be modified if the XPath
+// expression has no result.
static void xpath_get_int(int *out, xmlNodePtr node, const char *xpathExpr,
xmlXPathContextPtr xpathCtx) {
const char *s;
@@ -102,12 +114,16 @@ static void xpath_get_int(int *out, xmlNodePtr node, const char *xpathExpr,
*out = atoi(s);
}
+// Evaluate an XPath expression and store the result as a string. The
+// value pointed by out won't be modified if the XPath expression has
+// no result. The string will always use newly allocated memory.
static void xpath_get_string(char **out, xmlNodePtr node,
const char *xpathExpr,
xmlXPathContextPtr xpathCtx) {
*out = strdup(xpath_value_as_string(node, xpathExpr, xpathCtx));
}
+// Count the number of nodes returned by an XPath expression.
static int xpath_count(xmlNodePtr node, const char *xpathExpr, xmlXPathContextPtr xpathCtx) {
xmlXPathObjectPtr res;
int n;
@@ -134,12 +150,15 @@ static char *path_dirname(const char *filename) {
return buf;
}
+// Join two path components. Return a newly allocated string.
static char *path_join(const char *base, const char *filename) {
char *buf = (char *)malloc(strlen(base) + strlen(filename) + 2);
sprintf(buf, "%s/%s", base, filename);
return buf;
}
+// Load audio file data into a sample. Will convert the sample rate to
+// the desired target using libsamplerate.
static int load_sample_data(struct sample *sample, SNDFILE *sndfile, int target_samplerate) {
SF_INFO *info = &sample->info;
float *tmp, *p, *wl, *wr;
@@ -192,24 +211,25 @@ static int load_sample_data(struct sample *sample, SNDFILE *sndfile, int target_
return 1;
}
+// Load an audio file into a sample. Will convert the sample rate to
+// the desired target using libsamplerate.
static int load_sample(struct sample *sample, const char *path, int target_samplerate) {
SF_INFO *info = &sample->info;
SNDFILE *sndfile;
- int r = 1;
+ int r;
sndfile = sf_open(path, SFM_READ, info);
if (!sndfile) {
- printf("failed to open sample %s: %s\n", path, sf_strerror(NULL));
+ fprintf(stderr, "failed to open sample %s: %s\n", path, sf_strerror(NULL));
return 0;
}
- // Read all the sample data.
- if (!load_sample_data(sample, sndfile, target_samplerate)) {
- printf("failed to load sample data from %s\n", path);
- r = 0;
- }
-
+ // Read the sample data and convert it to the desired format/rate.
+ r = load_sample_data(sample, sndfile, target_samplerate);
sf_close(sndfile);
+ if (!r) {
+ fprintf(stderr, "failed to load sample data from %s\n", path);
+ }
return r;
}
@@ -222,6 +242,7 @@ static void free_sample(struct sample *sample) {
}
}
+// Parse an instrument layer from an XML document.
static int parse_layer(struct layer *layer, xmlNodePtr node,
xmlXPathContextPtr xpathCtx, const char *basedir,
int target_samplerate) {
@@ -246,6 +267,7 @@ static void free_layer(struct layer *layer) {
free_sample(&layer->sample);
}
+// Parse an instrument from an XML document.
static int parse_instrument(struct instrument *ins, xmlNodePtr node,
xmlXPathContextPtr xpathCtx, const char *basedir,
int target_samplerate) {
@@ -309,17 +331,19 @@ static void free_instrument(struct instrument *ins) {
free(ins->name);
}
+// Find the instrument layer corresponding to a specific velocity.
struct layer *instrument_find_layer_by_velocity(struct instrument *ins, float velocity) {
int i;
for (i = 0; i < ins->num_layers; i++) {
- if (ins->layers[i].max > velocity) {
+ if (velocity >= ins->layers[i].min && velocity <= ins->layers[i].max) {
return &ins->layers[i];
}
}
return &ins->layers[ins->num_layers - 1];
}
+// Parse a list of instruments from an XML document.
static int parse_instruments(struct instrument **instruments,
xmlNodeSetPtr nodes, xmlXPathContextPtr xpathCtx,
const char *basedir, int target_samplerate) {
@@ -345,7 +369,11 @@ static void free_instruments(struct instrument *instruments, int n) {
}
}
-void fix_midi_notes(struct drumkit *kit) {
+// Some drumkits lack an explicit MIDI note assignment: these are
+// recognizable because they set all instruments to the same MIDI
+// note. We can detect this situation and fix it with a default note
+// assignment.
+static void fix_midi_notes(struct drumkit *kit) {
int note_count[127] = {0};
int note_cardinality = 0;
int i;
@@ -377,6 +405,7 @@ struct drumkit *drumkit_new(const char *filename, int target_samplerate) {
return kit;
}
+// Assign the Hydrogen drumkit namespace to all XML nodes in a document.
static void fix_bad_xml(xmlNodePtr cur, xmlNsPtr ns) {
for (; cur; cur = cur->next) {
if (cur->type == XML_ELEMENT_NODE) {