diff options
Diffstat (limited to 'firmware/usbdrv')
| -rw-r--r-- | firmware/usbdrv/usbdrvasm165.inc | 43 |
1 files changed, 37 insertions, 6 deletions
diff --git a/firmware/usbdrv/usbdrvasm165.inc b/firmware/usbdrv/usbdrvasm165.inc index ae91588..450d2fd 100644 --- a/firmware/usbdrv/usbdrvasm165.inc +++ b/firmware/usbdrv/usbdrvasm165.inc @@ -4,7 +4,9 @@ * Creation Date: 2007-04-22 * Tabsize: 4 * Copyright: (c) 2007 by OBJECTIVE DEVELOPMENT Software GmbH + * Portions Copyright: (c) 2012 Louis Beaudoin * License: GNU GPL v2 (see License.txt), GNU GPL v3 or proprietary (CommercialLicense.txt) + * Revision: $Id: usbdrvasm165.inc 740 2009-04-13 18:23:31Z cs $ */ /* Do not link this file! Link usbdrvasm.S instead, which includes the @@ -34,12 +36,41 @@ of CPU cycles, but even an exact number of cycles! ; Numbers in brackets are clocks counted from center of last sync bit ; when instruction starts +; the code enabled by TINY85MODE is inteded only for use with the tiny85-compatible USBaspLoader +; project. +; with TINY85MODE set, the beginning of the ISR checks for a magic word "B007" at the very bottom of the stack +; and jumps to the application's ISR if the magic word isn't present +; the max allowable interrupt latency is lower given this additional code before getting to the +; USB-specific portion of the ISR. USB_INTR_VECTOR: ;order of registers pushed: YL, SREG [sofError], r0, YH, shift, x1, x2, x3, x4, cnt - push YL ;[-23] push only what is necessary to sync with edge ASAP - in YL, SREG ;[-21] - push YL ;[-20] + push YL ; push only what is necessary to sync with edge ASAP + in YL, SREG ; + push YL ; + +#ifdef TINY85MODE +; look for magic word "B007" at the bottom of the stack + lds YL, RAMEND + cpi YL, 0xB0 + brne cleanupAndJumpToApp + + lds YL, RAMEND-1 + cpi YL, 0x07 + breq cleanupBootloaderIntStack + +cleanupAndJumpToApp: +; magic word was not found, put registers back to where they were before this ISR ran, and jump to application ISR + pop YL + out SREG, YL + pop YL + + rjmp __vectors - TINYVECTOR_USBPLUS_OFFSET + +cleanupBootloaderIntStack: +; magic word was found, put registers + CLR YL ; [-19] ensure we meet below requirements for YL < 0x80 +#endif ;---------------------------------------------------------------------------- ; Synchronize with sync pattern: ;---------------------------------------------------------------------------- @@ -49,9 +80,9 @@ USB_INTR_VECTOR: ;YL is guarenteed to be < 0x80 because I flag is clear. When we jump to ;waitForJ, ensure that this prerequisite is met. waitForJ: - inc YL - sbis USBIN, USBMINUS - brne waitForJ ; just make sure we have ANY timeout + inc YL ; [-18] + sbis USBIN, USBMINUS ; [-17] + brne waitForJ ; [-16] just make sure we have ANY timeout waitForK: ;The following code results in a sampling window of < 1/4 bit which meets the spec. sbis USBIN, USBMINUS ;[-15] |