X-Git-Url: https://notaz.gp2x.de/cgi-bin/gitweb.cgi?p=fceu.git;a=blobdiff_plain;f=drivers%2Fgp2x%2Fasmutils.s;fp=drivers%2Fgp2x%2Fasmutils.s;h=917bb0892f9771a004222b3bc5cff090338f288a;hp=c87a3ab3327da3244f5b4a97c856618531100513;hb=c0bf6f9f02a2b6afb961a7e9195e2168d7e9cecf;hpb=4e1934c1ee3a43796e68edc66b3c3f8e079caf7c

diff --git a/drivers/gp2x/asmutils.s b/drivers/gp2x/asmutils.s
index c87a3ab..917bb08 100644
--- a/drivers/gp2x/asmutils.s
+++ b/drivers/gp2x/asmutils.s
@@ -7,3 +7,60 @@ flushcache:
     swi #0x9f0002
     mov pc, lr
 
+
+/* buggy and slow, probably because function call overhead
+@ renderer helper, based on bitbank's method
+.global draw8pix @ uint8 *P, uint8 *C, uint8 *PALRAM @ dest, src, pal
+
+draw8pix:
+    stmfd sp!, {r4,r5}
+
+    ldrb  r3, [r1]            @ get bit 0 pixels
+    mov   r12,#1
+    orr   r12,r12,r12,lsl #8
+    orr   r12,r12,r12,lsl #16
+    ldrb  r1, [r1, #8]        @ get bit 1 pixels
+    orr   r3, r3, r3, lsl #9  @ shift them over 1 byte + 1 bit
+    orr   r3, r3, r3, lsl #18 @ now 4 pixels take up 4 bytes
+    and   r4, r12,r3, lsr #7  @ mask off the upper nibble pixels we want
+    and   r5, r12,r3, lsr #3  @ mask off the lower nibble pixels we want
+    ldr   r2, [r2]
+
+    orr   r1, r1, r1, lsl #9  @ process the bit 1 pixels
+    orr   r1, r1, r1, lsl #18
+    and   r3, r12,r1, lsr #7  @ mask off the upper nibble pixels we want
+    and   r1, r12,r1, lsr #3  @ mask off the lower nibble
+    orr   r4, r4, r3, lsl #1
+    orr   r5, r5, r1, lsl #5
+
+    @ can this be avoided?
+    mov   r4, r4, lsl #3      @ *8
+    mov   r3, r2, ror r4
+    strb  r3, [r0], #1
+    mov   r4, r4, lsr #8
+    mov   r3, r2, ror r4
+    strb  r3, [r0], #1
+    mov   r4, r4, lsr #8
+    mov   r3, r2, ror r4
+    strb  r3, [r0], #1
+    mov   r4, r4, lsr #8
+    mov   r3, r2, ror r4
+    strb  r3, [r0], #1
+
+    mov   r5, r5, lsl #3      @ *8
+    mov   r3, r2, ror r5
+    strb  r3, [r0], #1
+    mov   r5, r5, lsr #8
+    mov   r3, r2, ror r5
+    strb  r3, [r0], #1
+    mov   r5, r5, lsr #8
+    mov   r3, r2, ror r5
+    strb  r3, [r0], #1
+    mov   r5, r5, lsr #8
+    mov   r3, r2, ror r5
+    strb  r3, [r0], #1
+
+    ldmfd sp!, {r4,r5}
+    bx    lr
+*/
+