Optimize ff2ppm(1)

use the proper multiplication factors :)

1 files changed, 27 insertions, 36 deletions

diff --git a/ff2ppm.c b/ff2ppm.c
index 7f6aa61..09eb346 100644
--- a/ff2ppm.c
+++ b/ff2ppm.c
@@ -23,45 +23,33 @@ int
 main(int argc, char *argv[])
 {
 	size_t rowlen;
-	uint32_t hdr[4], width, height, i, j, k;
-	uint16_t *row, mr = 0xffff, mg = 0xffff, mb = 0xffff;
+	uint64_t a;
+	uint32_t hdr[4], width, height, i, j, k, l;
+	uint16_t *row, mask[3] = { 0xffff, 0xffff, 0xffff };
 	uint8_t *rowout;
-	char *color;
-	unsigned int r = 0xff, g = 0xff, b = 0xff;
-	float a;
+	char *color, colfmt[] = "%#x%#x%#x";
+	unsigned int collen, col[3], colfac;
 
 	argv0 = argv[0];
 	ARGBEGIN {
 	case 'b':
-		for (color = EARGF(usage()); *color && *color == '#'; color++)
-			;
-
-		switch (strlen(color)) {
-		case 3:
-			if (sscanf(color, "%1x%1x%1x", &r, &g, &b) != 3)
-				usage();
-			mr = (r | r << 4) * 257;
-			mg = (g | g << 4) * 257;
-			mb = (b | b << 4) * 257;
-			break;
-		case 6:
-			if (sscanf(color, "%2x%2x%2x", &r, &g, &b) != 3)
-				usage();
-			mr = r * 257;
-			mg = g * 257;
-			mb = b * 257;
-			break;
-		case 12:
-			if (sscanf(color, "%4x%4x%4x", &r, &g, &b) != 3)
-				usage();
-			mr = r;
-			mg = g;
-			mb = b;
-			break;
-		default:
+		color = EARGF(usage());
+		if (color[0] == '#') {
+			color++;
+		}
+		collen = strlen(color);
+		if (collen != 3 && collen != 6 && collen != 12) {
+			usage();
+		}
+		colfmt[1] = colfmt[4] = colfmt[7] = ((collen / 3) - '0');
+		if (sscanf(color, colfmt, col, col + 1, col + 2) != 3) {
 			usage();
 		}
-		break;
+		/* UINT16_MAX / 255 = 257; UINT16_MAX / 15 = 4369 */
+		colfac = (collen == 3) ? 4369 : (collen == 6) ? 257 : 1;
+		for (i = 0; i < 3; i++) {
+			mask[i] = col[i] * colfac;
+		}
 	default:
 		usage();
 	} ARGEND
@@ -111,15 +99,18 @@ main(int argc, char *argv[])
 			return 1;
 		}
 		for (j = 0, k = 0; j < rowlen; j += 4, k += 3) {
-			a = ntohs(row[j + 3]) / 65535.0f;
-			rowout[k]     = ((ntohs(row[j]) * a)     + (mr * (1 - a))) / 257;
-			rowout[k + 1] = ((ntohs(row[j + 1]) * a) + (mg * (1 - a))) / 257;
-			rowout[k + 2] = ((ntohs(row[j + 2]) * a) + (mb * (1 - a))) / 257;
+			a = ntohs(row[j + 3]);
+			for (l = 0; l < 3; l++) {
+				rowout[k + l] = (a * ntohs(row[j + l]) +
+				                 (65535 - a) * mask[l]) /
+				                (257 * 65535);
+			}
 		}
 		if (fwrite(rowout, 3, width, stdout) != width) {
 			fprintf(stderr, "%s: fwrite: %s\n", argv0, strerror(errno));
 			return 1;
 		}
 	}
+
 	return 0;
 }